Docs: Release strategy for patch/minor versions during development of next major release about pharos

[daneah]

Some inspiration from Django

[daneah]

As an anecdote, we took the approach of keeping a long-running release/14.0.0 branch going to allow develop to continue getting non-breaking features, and merging breaking features into the release branch. This worked okay, but with a few impacts:

• We would forget to merge develop into the release branch regularly, creating hairy merge conflicts
  • The release branch is in general divergent from develop, so we get more merge conflicts no matter what we do
• Atlassian Changesets seems to read commit authors rather than looking at PR authors, and because we squash commits it looked like @brentswisher had done all the work when it came time to release after merging release/14.0.0 into develop.