MFC r233473,233512,233518,233992,233994,238808,238920,250209-250211.

libc/locale: sync mdoc changes with head.

 r233473:
  mdoc: document title should be all caps.

 r233512:
  mdoc: remove empty lines.

 r233518:
  mdoc: remove unknown macro.

 r233992:
  mdoc: fix column names, indentation, column separation within each row, and
  quotation. Also make sure we have the same amount of columns in each row as
  the number of columns we specify in the head arguments.

 r233994:
  mdoc: fix function type.

 r238808:
  Start manpage with Dd macro and also remove a trailing whitespace
  while here.

 r238920:
  Remove trailing whitespace.

 r250209:
  querylocale(3): remove the STANDARDS section.

 r250210,r250211:
  Remove an extra comma, add a missing period.