Updates for README, docker config and environment

[chetanyb]

Description

• Added a step-by-step guide in the README for installing the necessary tools to run matic-cli locally on macOS using Docker.
• Corrected minor typos in the existing documentation for improved clarity.
• Additional changes in README, docker config and env.example for better clarity and GCP support info

Changes

• Bugfix (non-breaking change that solves an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (change that is not backwards-compatible and/or changes current functionality)
• New test case for remote devnet

Checklist

• I have added at least 2 reviewer or the whole pos-v1 team
• I have added sufficient documentation in code
• I will be resolving comments - if any - by pushing each fix in a separate commit and linking the commit hash in the comment reply

Cross repository changes

It should never be the case...

• This PR requires changes to bor
  • In case link the PR here:
• This PR requires changes to heimdall
  • In case link the PR here:

Testing

• I have tested this code manually on local environment
• I have tested this code manually on remote devnet using express-cli
• I have tested this code manually on mumbai or amoy

Manual tests

Please complete this section with the steps you performed if you ran manual tests for this functionality, otherwise delete it

Additional comments

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