ipaserver docs: Calm down module linter

The use of "default: idstart+199999" in the description of the idmax
parameter was resulting in the galaxy import error:

  Cannot parse "DOCUMENTATION": mapping values are not allowed here in
  "<unicode string>", line 52, column 58: ... value for the IDs range
  (default: idstart+199999)

The ":" has simply been removed to fix this issue.