Small change: JS SDK documentation - add the commands and file formats for running the examples

[6r1d]

Requested by Denis Kitaev from HL Iroha community while trying the JS tutorial step-by-step.

kidys@ubuntusrv:~/iroha2-javascript$ tsx src/index.ts

node:internal/process/esm_loader:97
    internalBinding('errors').triggerUncaughtException(
                              ^

Error: Transform failed with 1 error:
/home/kidys/iroha2-javascript/src/index.ts:30:15: ERROR: Top-level await is currently not supported with the "cjs" output format

Since this error is common enough, I won't describe the specifics now.

[dmitrivenger]

@0x009922 is this task still relevant?

[nxsaken]

Related to hyperledger-iroha/iroha-javascript#199?