fix #10857: how to create a PR that changes the schema
Emphasise necessary of patch++ and discuss SQL upgrade scripts.
adjustments prompted by Helen's suggestions
fix #10870: describe FS upload configuration
Fix OMERO version number generation

- Fix a bug in the server upgrade page where the previous version number was
calculated to 5.-1
- Correctly parse the version numbers using semver.org conventions
- Define list of previous minor versions for each major version
- Do not import the re module globally
act on Helen's suggestions, clarify titles, handle end-of-files
merge develop -D org -I include -E exclude: PR 364 (fix #10857: how to create a PR that changes the schema (rebased onto develop))
merge develop -D org -I include -E exclude: PR 365 (fix #10870: describe FS upload configuration)
merge develop -D org -I include -E exclude: PR 366 (Fix OMERO version number generation)