Update mapper documenation for match helper [ci skip]
This piece of documentation is out of date.
The use of match without any via option is prevented, now
the HTTP verbs have to be explicitly set. If they're not set then
the error message in normalize_conditions! (around line 186) is
shown.
Merge pull request #12077 from estsauver/doc_fix

Update mapper documenation for match helper [ci skip]