So I think I know all the GIT meta-data file types, stolen from stackoverflow:

• .gitignore - List of blobs for git to ignore. Affects commands like git add and git clean.
• .gitattributes - Let’s you define attributes on files (e.g., to change how files look in a diff).
• .mailmap - Lets you tell git that duplicate names or emails in the history are actually the same person. Affects commmands like git shortlog -ns, or git log --format="%aN <%aE>".
• .gitmodules  - Let’s you define submodules (subdirectories of your git repository which are checkouts of other git repositories).
• *.keep  - Something to do with making git gc ignore packs. I couldn’t find much info on this, so I’m not even sure if it’s a file that you commit to the repository or just something that lives in .git. 

But what are the github specific meta files.  All I know of right now are:

• .github/README.md - The default readme rendered on your main repo page
• .github/ISSUE_TEMPLATE  - The template use for new issue creation.
• docs/  - Folder used to render Github Pages jekyll matter.

Any others that anyone could add, or correct?