Migration of CodeQL CLI Docs to GitHub Docs site

Following feedback from code scanning users, we've moved documentation about the CodeQL CLI from codeql.github.com to docs.github.com, the main GitHub Docs site.

You can now find the articles under the “Using the CodeQL CLI” and “CodeQL CLI reference” categories, which correspond to the categories on the original site. We’ve updated each of the original articles on codeql.github.com with links to the new location of the article and to each subsection, so that if you go to the old location you can easily find the information you need.

The source files now exist in Markdown format in the public, open-source docs repository. If you would like to contribute, you can consult and follow the steps listed in the GitHub Docs contributing guide.