Change from master to main

[Dynnammo]

This is a 🔦 documentation change.

Summary

In the documentation, there's a lot of references to old named branches master. This PR correct them by renaming them main. Noteworthy : I didnt' change any coding files (or if so, it was only things commented) in order not to break anything, but with review help I can also manage it if wanted.

Context

Fix #642

[andrewmcodes]

@Dynnammo this changes all look excellent to me. Thanks for doing this!

I didnt' change any coding files (or if so, it was only things commented) in order not to break anything, but with review help I can also manage it if wanted.

I'd be happy to review. Perhaps open a new PR so this one can be reserved for documentation & internal utilities?

[jaredcwhite]

Thanks @Dynnammo!

[Dynnammo]

Wow just woke up to read all this, it ain't much but it's honest work, happy to be reviewed by the two heroes of the Bridgetownconf 🤯 . I'm also working on this related issue concerning GitLab deployment, if you have some insights or could give any advice or redirect me to any documentation that might help : #643