feat: Improve Standby docs (#1150)

There were some questions on Discord how to find out if an Actor is
started in Standby mode, or normally. This should answer them.

I've also added a tip about Standby in the Container web server docs.

This needs apify/apify-sdk-js#320 released.

Author: fnesveda

sources/platform/actors/development/programming_interface/actor_standby.md

@@ -72,6 +72,44 @@ async def main() -> None:
 Please make sure to describe your Actors, their endpoints, and the schema for their
 inputs and outputs in your README.
 
+## How do I find out whether my Actor is started in Standby or standard mode
+
+Actors that support Actor Standby can still be started in standard mode, for example from the Console or via the API.
+To find out in which mode was the Actor started, you can read the `metaOrigin` option in `Actor.config`, or the `APIFY_META_ORIGIN` environment variable in case you're not using the Apify SDK.
+If it is equal to `STANDBY`, the Actor was started in Standby mode, otherwise it was started in standard mode.
+
+<Tabs groupId="main">
+<TabItem value="JavaScript" label="JavaScript">
+
+```js
+import { Actor } from 'apify';
+
+await Actor.init();
+
+if (Actor.config.get('metaOrigin') === 'STANDBY') {
+    // Start your Standby server here
+} else {
+    // Perform the standard Actor operations here
+}
+```
+
+</TabItem>
+<TabItem value="Python" label="Python">
+
+```python
+from apify import Actor
+
+async def main() -> None:
+    async with Actor:
+        if Actor.config.meta_origin == 'STANDBY':
+            # Start your Standby server here
+        else:
+            # Perform the standard Actor operations here
+```
+
+</TabItem>
+</Tabs>
+
 ## Can I monetize my Actor in the Standby mode
 
-No, Standby mode is in Beta, and monetization is not supported.
+No, Standby mode is in Beta, and monetization is currently not supported.

sources/platform/actors/development/programming_interface/container_web_server.md

@@ -14,6 +14,12 @@ import TabItem from '@theme/TabItem';
 
 Each Actor run is assigned a unique URL (e.g. `kmdo7wpzlshygi.runs.apify.net`) that allows HTTP access to an optional web server running inside the Actor's Docker container. This feature enhances your Actor's capabilities by enabling external communication.
 
+:::tip Using Actors as an API
+
+The container web server provides a way how to connect to one specific Actor run. To enable using your Actor as an API, with a pre-defined hostname, load balancing and autoscaling, check out [Actor Standby](./actor_standby.md).
+
+:::
+
 ## Access the container URL
 
 You can find the container URL in three locations:

sources/platform/actors/running/runs_and_builds.md

@@ -50,6 +50,7 @@ All **Actor runs** have an **Origin** field indicating where the Actor run was i
 |SCHEDULER|Using a Schedule|
 |WEBHOOK|Using a webhook|
 |ACTOR|From another Actor run|
+|STANDBY|From Actor Standby|
 
 ## Lifecycle