Add credential manager setup instructions

[parkerbxyz]

I’d like to add a page that outlines how to set up Git Credential Manager for use in different environments.

macOS

git config --global credential.helper osxkeychain

Windows

git config --global credential.helper wincred

Windows Subsystem for Linux (WSL)

To set up Git Credential Manager for use with a WSL distribution, open your distribution and enter this command:

git config --global credential.helper "/mnt/c/Program\ Files/Git/mingw64/libexec/git-core/git-credential-manager.exe"

[beardofedu]

@parkerbxyz , do you think this should live in the "Tool tips" section as a single page or as a section in the Local Git Configs section?

[parkerbxyz]

I think either of those would be good places for it. Do you have a preference, @beardofedu?

[beardofedu]

I think Local Configs might be the play, I can add that pretty quickly, especially since you already identified most of the heavy lifting 😄

[whatupfoo]

these instructions are on this page: https://githubtraining.github.io/training-manual/#/07_collaborating_on_code?id=collaborating-on-your-code if you want to move it to another section

[beardofedu]

@rwnfoo I thought they might already exist, I can just make it a more prominent section and leave it right with the first push