[documentation]: Review the Iroha 2 vs. Iroha 1 chapter

Signed-off-by: Ekaterina Mekhnetsova <mekkatya@gmail.com>

Author: outoftardis

src/guide/iroha-2.md

@@ -3,75 +3,93 @@
 Iroha 2 is a complete re-write of Hyperledger Iroha in Rust. As of writing
 the two projects are developed concurrently.
 
+Here we aspire to outline the differences between two versions of Iroha and
+highlight the new features of Iroha 2. This introduction should be of
+particular interest to those who are already familiar with Iroha but wish
+to upgrade and start using the newer version.
+
+<!-- This list of headlining features goes on. As we are nearing our first
+long-term supported preview release, we'll be updating the guide with
+relevant changes. -->
+
 ## Fault Tolerance
 
 Iroha 2 learned a great deal from the development of the original Iroha. Of
 particular importance is the new and improved Byzantine-fault-tolerant
 consensus algorithm: _Sumeragi_. This new consensus allowed us to expand
-what could be done on a blockchain, without any security risks.
+what could be done on a blockchain without any security risks.
 
 ::: info
 
-The first version of Iroha used a consensus algorithm called _Yac_. It is
-_crash-fault-tolerant_, which means that it can survive a set number of
+The first version of Iroha used a consensus algorithm called _Yac_. _Yac_
+is _crash-fault-tolerant_, which means that it can survive a set number of
 nodes _crashing_: i.e. losing power, being cut off from the network, or
-being destroyed with a sledgehammer. _Sumeragi_, by contrast, was designed
-to be _Byzantine-fault-tolerant_. This means that Iroha 2 can tolerate not
-only peers being inactive on the network, but also running malicious
-software, and actively trying to falsify data in the blockchain.
+being destroyed with a sledgehammer.
+
+_Sumeragi_, by contrast, was designed to be _Byzantine-fault-tolerant_.
+This means that Iroha 2 can tolerate not only peers being inactive on the
+network, but also running malicious software and actively trying to falsify
+data in the blockchain.
 
-We can mathematically prove that **Iroha 2 can work when up to 33% of its
-nodes are actively trying to stop Iroha 2 from working properly** (_or at
-all_). In other words, even if someone gained control of a _third_ of all
-of your network nodes, an Iroha 2 deployment is _mathematically guaranteed_
-to keep working.
+We can mathematically prove that Iroha 2 can work when **up to 33%** of its
+nodes are actively trying to stop Iroha 2 from working properly or at all.
+In other words, even if someone gained control of a _third_ of all of your
+network nodes, an Iroha 2 deployment is _mathematically guaranteed_ to keep
+working.
 
 :::
 
 ## Minimalist Code Base
 
 Iroha 2 is a minimalist code base. We take great care to vet our
-dependencies, and avoid large inter-dependent chunks of code. We provide a
-few telemetry APIs, including `prometheus` tooling, structured logging in
-JSON, as well as compatibility with
-[standard tools](https://wiki.sora.org/sora-faq) used in Parity Substrate.
-Our data is strongly-typed, and our methods — statically dispatched. We
-make use of the best that Rust has to offer: `serde` and
-`parity_scale_codec` for serialisation, `tokio` for co-operative
-multi-threading, as well as wealth of testing, bench-marking, static
-analysis and code auditing tools that come packaged with the exemplary
-`cargo`. Our code is easy to reason about, and quick to compile, whilst
-also being ergonomic to use and thoughtfully crafted. We have no `panics`
-and no `unsafe` code.
+dependencies and avoid large inter-dependent chunks of code.
+
+We provide a few telemetry APIs, including `prometheus` tooling, structured
+logging in JSON, as well as compatibility with standard tools used in
+Parity Substrate.
+
+Our data is strongly-typed, our methods are statically dispatched. We make
+use of the best that Rust has to offer: `serde` and `parity_scale_codec`
+for serialisation, `tokio` for co-operative multi-threading, as well as
+testing, bench-marking, static analysis and code auditing tools that come
+packaged with the exemplary `cargo`.
+
+Our code is easy to reason about, and quick to compile, whilst also being
+ergonomic to use and thoughtfully crafted. We have no `panics` and no
+`unsafe` code.
 
 ## Flexibility
 
-Iroha 2 is also more flexible than the original Iroha due to modular
-design. It is possible to add or remove features based on the particular
-use-case. If you want to be extremely fast, and work on embedded hardware,
+Iroha 2 is also more flexible than the original Iroha due to its modular
+design.
+
+It is possible to add or remove features based on a particular use-case. If
+you want the blockchain to be extremely fast and work on embedded hardware,
 just compile Iroha 2 without the `expensive-metrics` feature. Don't use
 telemetry at all? Remove it entirely and enjoy even more performance.
-_Permission_ sets are plugins that can be upgraded during run-time. We have
-an extensive module system as well as a robust WASM runtime framework.
+_Permission_ sets are plugins that can be upgraded during run-time.
+
+We have an extensive module system as well as a robust WASM runtime
+framework.
 
 ## Smart Contracts
 
 Iroha 2 is an event-driven ledger. Each change in the state of the
 blockchain is necessarily accompanied by its own event that can _trigger_ a
-smartcontract: complex logic designed for use in on-chain scripting.
+smart contract: complex logic designed for use in on-chain scripting.
 
 For smart contracts, Iroha 2 supports two approaches:
 
 - [Iroha Special Instructions (ISI)](./advanced/isi.md)
 - [Web ASseMbly (WASM)](./advanced/wasm.md)
 
-The first approach is useful when you want very simple transparent logic,
-and want to minimise the footprint in the blockchain. All interactions with
-the _World state_, that is, the state of the blockchain at this point in
-time, has to be done using the aforementioned instructions. There is also
-rudimentary support for domain-specific conditional logic.
+The first approach is useful when you want very simple transparent logic
+and also want to minimise the footprint in the blockchain. All interactions
+with the _World state_, that is, the state of the blockchain at this point
+in time, has to be done using the aforementioned instructions. There is
+also rudimentary support for domain-specific conditional logic.
 
-If you want to learn more about smartcontracts in Iroha 2, please consult
+If you want to learn more about smart contracts in Iroha 2, please consult
 our
 [Wiki](https://wiki.hyperledger.org/display/iroha/Scripting+Languages+and+Runtimes+for+Iroha2+Smart+Contracts).
 
@@ -82,7 +100,7 @@ our
 Iroha 2 smartly chooses when to use dynamic linking. This strikes a balance
 between it being easy to patch a Critical security vulnerability in a
 vendored library like OpenSSL, but also remaining reproducible and portable
-across platforms, architectures and deployments.
+across platforms, architectures, and deployments.
 
 ::: info
 
@@ -97,11 +115,12 @@ Iroha after an upgrade.
 ## Testing
 
 Iroha 2 is extensively tested. Despite being in active development, Iroha
-has 80% line coverage (keep in mind, line coverage includes documentation
-comments, some of which are also tests). There are plans to include Fuzz
-testing, property-based testing and failure-point testing to ensure that
-Iroha is reliable.
+has 80% line coverage. Keep in mind that line coverage includes
+documentation comments, some of which are also tests.
 
-The list of headlining features goes on. As we are nearing our first
-long-term supported preview release, we'll be updating the guide with
-relevant changes.
+::: info
+
+There are plans to include Fuzz testing, property-based testing, and
+failure-point testing to ensure that Iroha is reliable. <!-- Check -->
+
+:::