chore: fixing some docs

[Neurone]

Description:

Fixing some docs, especially the need for --recursive parameter when cloning the repo.

Related issue(s):

Fixes later compilation errors if you don't include submodules in the repo.

   Compiling hedera-proto v0.8.1 (/home/developer/workspace/hedera/hedera-sdk-rust/protobufs)
error: failed to run custom build command for `hedera-proto v0.8.1 (/home/developer/workspace/hedera/hedera-sdk-rust/protobufs)`

Caused by:
  process didn't exit successfully: `/home/developer/workspace/hedera/hedera-sdk-rust/target/debug/build/hedera-proto-1822a64e67ed6dbd/build-script-build` (exit status: 1)
  --- stderr
  Error: No such file or directory (os error 2)
warning: build failed, waiting for other jobs to finish...

Notes for reviewer:
N/A

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[RickyLB]

@Neurone Just need you to sign the commit please then let's get this merged!

[Neurone]

Yep, sure. Done!