CMake Nightly Date Stamp
string: Fix regex documentation of '^' and '$' (#14028)

They match at the beginning and end of the input, not by line.

Reported-by: Martin Perzl <martin.perzl@web.de>
Merge topic 'doc-string-regex' into next

763a6dc string: Fix regex documentation of '^' and '$' (#14028)
5dfa624 CMake Nightly Date Stamp