Add git insteadof example

[multimeric]

Closes #270.

[Copilot]

Pull Request Overview

This PR adds documentation for configuring Git to use GitHub App tokens for authentication, addressing issue #270. The addition provides guidance for scenarios where tools use Git directly but cannot accept GitHub API tokens.

• Adds a new documentation section explaining Git's insteadof configuration option
• Provides a complete workflow example for Python projects with private Git dependencies
• Includes additional configuration examples for repository and organization-specific authentication

[Copilot]

The placeholder 'USERNAME' in the Git URL is not explained. Consider clarifying what value should be used here or if it's a literal placeholder that Git ignores for token-based authentication.

Suggested change

	- name: Configure git to use the app token
	- name: Configure git to use the app token
	# The USERNAME part of the URL can be any non-empty string (e.g., 'x-access-token'), as GitHub ignores it when a token is used.

[Copilot]

This example uses the same unexplained 'USERNAME' placeholder. For consistency and clarity, this should match the explanation provided for the main example above.

Suggested change

	git config --global url."https://USERNAME:${GITHUB_TOKEN}@github.com/MyOrg/MyRepo".insteadOf "https://github.com/MyOrg/MyRepo"
	git config --global url."https://x-access-token:${GITHUB_TOKEN}@github.com/MyOrg/MyRepo".insteadOf "https://github.com/MyOrg/MyRepo"

[github-actions]

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[parkerbxyz]

Hi @multimeric, thanks for your patience. After reviewing this, I think there's a simpler solution:

- uses: actions/create-github-app-token@v3
  id: app-token
  with:
    client-id: ${{ vars.GITHUB_APP_CLIENT_ID }}
    private-key: ${{ secrets.GITHUB_APP_PRIVATE_KEY }}

- name: Configure git to use the app token
  run: gh auth setup-git
  env:
    GH_TOKEN: ${{ steps.app-token.outputs.token }}

This uses the GitHub CLI (pre-installed on GitHub-hosted runners) to configure Git's credential helper. When subsequent steps run git operations, they'll authenticate via gh. Just make sure GH_TOKEN is set on those steps too.

Do you think this would work for your use case? Looks like #287 proposes something very close to this.