Add documentation for Github CLI setup

[Mahita07]

Please make sure to read the Contributing Guidelines:

https://github.com/neomjs/neo/blob/dev/CONTRIBUTING.md

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe: documentation

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch, not the main branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:
This PR has the changes required to

• add new documentation for creating a GitHub PAT with required scope and using it with the Github CLI.
• reference the GitHub CLI setup guide in AGENTS.md as a prerequisite.
• Find the issue here

[Mahita07]

@tobiu could you please review this PR ?

[tobiu]

Thx for your contribution! It does fulfill the ticket scope.

Thinking more about the topic, I will create a small follow-up ticket tomorrow. If you like, you can get it assigned and it would count for another hacktoberfest PR. Here is the idea: While we can explore all md files (like your new guide) inside the repo, we can also see the content inside the neo website (apps/portal). So the follow-up item would be:
adding the guide in here: https://github.com/neomjs/neo/blob/dev/learn/tree.json, changing the file location to learn/guides/ai, and adding a small new section about the gitignored .env file inside the repo. since devs already add their gemini key in there, it would be a logical place to also store a GH token in it (optionally).

Feedback from Gemini (sadly I am out of tokens for today, so this is the flash model):

PR Summary

This pull request introduces a new file, learn/guides/development/GitHubCLISetup.md, and modifies
AGENTS.md.

• learn/guides/development/GitHubCLISetup.md: This new guide provides detailed instructions on
  how to set up the GitHub CLI using a Personal Access Token (PAT), emphasizing fine-grained PATs
  and secure authentication.
• AGENTS.md: A new Step 8, "Read the Github CLI Setup Guide," is added to the "Session
  Initialization" section, and subsequent steps are renumbered.

Analysis

• Ticket Fulfillment:

  • The new GitHubCLISetup.md file fully and excellently resolves ticket-setup-github-cli-authentication.md.
  • The AGENTS.md modification correctly integrates this new setup guide into my initialization workflow, ensuring I am aware of the GitHub CLI setup process.

• Documentation Quality: Both the new guide and the AGENTS.md update are clear, well-structured,
  and provide actionable information. The guide's emphasis on security best practices
  (fine-grained PATs, least privilege) is particularly commendable.

• Dependencies: This PR is foundational. It creates the necessary documentation for setting up the
  GitHub CLI, which is a prerequisite for all subsequent gh-based automation tasks.

Recommendation

Accept the PR.

This is an excellent and crucial contribution. It establishes the foundational documentation for
GitHub CLI setup, which is essential for the entire integration epic.

[Mahita07]

Please assign me to the follow up ticket as well. I'd be glad to continue working on it.