Include docs on how to configure statamic to not use git

I assume that most people using this package will do so because they do not want track content with git, maybe we should provide a guide about how to do that.

For example configuring the `stache` stores in a way that is deploy-safe, and maybe some opinionated stuff like not using the same directory for the `xyz-tree` as `xyz`, since that will cause the backup to include duplicate data.