Docs: Add documentation for editing permissions in Gitpod for GitHub open source contributions

[ll-zerr]

If an individual has never contributed to an organization in open source before, an error similar to this may occur when trying to push a commit to GitHub through Gitpod:
Pushing to https://github.com/distributeaid/aggregated-public-information.git
remote: Permission to distributeaid/aggregated-public-information.git denied to [my github username].
fatal: unable to access 'https://github.com/distributeaid/aggregated-public-information.git/': The requested URL returned error: 403

Issue Goals:

• Create documentation that provides steps to edit the permissions in "User Settings" for the GitHub Providers.
• Include screenshots for visual representation.