Add GitHub MCP Server setup instructions

[jacobsoto01121997]

Added installation instructions for GitHub MCP Server in Cursor, including prerequisites, setup steps, and troubleshooting tips.

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Progress

• [ ] Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• [x] Change must not contain extraneous whitespace

Error

 ⚠️ OCA signatory status must be verified

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/guide.git pull/161/head:pull/161
$ git checkout pull/161

Update a local copy of the PR:
$ git checkout pull/161
$ git pull https://git.openjdk.org/guide.git pull/161/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 161

View PR using the GUI difftool:
$ git pr show -t 161

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/guide/pull/161.diff

[bridgekeeper[bot]]

Hi @jacobsoto01121997, welcome to this OpenJDK project and thanks for contributing!

We do not recognize you as Contributor and need to ensure you have signed the Oracle Contributor Agreement (OCA). If you have not signed the OCA, please follow the instructions. Please fill in your GitHub username in the "Username" field of the application. Once you have signed the OCA, please let us know by writing /signed in a comment in this pull request.

If you already are an OpenJDK Author, Committer or Reviewer, please click here to open a new issue so that we can record that fact. Please use "Add GitHub user jacobsoto01121997" as summary for the issue.

If you are contributing this work on behalf of your employer and your employer has signed the OCA, please let us know by writing /covered in a comment in this pull request.

[openjdk[bot]]

❗ This change is not yet ready to be integrated. See the Progress checklist in the description for automated requirements.

[JesperIRL]

Who are the intended users here?