Some initial migration considerations for versions 2.0, 2.1, and 2.2

[shaneataylor]

Each version's changes is in a separate commit. These partially address #29. Hopefully we can build on this as a starting point.

[infotexture]

Thanks, this looks like a good starting point indeed.

In the context of migrations though, we should drop the trailing .0 from filenames and version references in the topic text, and just refer to 2.0, 2.1, 2.2, etc.

Maintenance releases typically include only bugfixes, and should not deprecate additional templates or include other significant changes that would require separate migration instructions. If there are exceptions, we can list them as such in the topic text, but otherwise it should be safe to assume that the process of migrating to 2.1, 2.1.1, or 2.1.2 is the same.