Expand a little.
- mention the type name of the return code
- avoid stating which exact return codes that might be returned, as that
varies over time, builds and conditions
- avoid stating some always return OK
- refer to the manpage documenting all the return codes
Closes#15900
- make DEFAULT sections less repetitive
- make historic mentions use HISTORY
- generate the protocols section on `# %PROTOCOLS%` instead of guessing
where to put it
- generate the availability section on `# %AVAILABILITY%` instead of
guessing where to put it
- make the protocols section more verbose
Closes#14227
- generate AVAILABILITY manpage sections automatically - for consistent
wording
- allows us to double-check against other documumentation (symbols-in-versions
etc)
- enables proper automation/scripting based on this data
- lots of them were wrong or missing in the manpages
- several of them repeated (sometimes mismatching) backend support info
Add test 1488 to verify "added-in" version numbers against
symbols-in-versions.
Closes#14217
