Utilities/Sphinx: Allow linkcheck redirect for our get-involved page

The `cmake.org/get-involved` URL is more semantically meaningful than
the `cmake.org/documentation` URL to which the former now redirects as
an implementation detail.

Utilities/Sphinx/conf.py.in

@@ -92,6 +92,7 @@ linkcheck_ignore = [r'about:|https://gitlab.kitware.com/cmake/community/-/wikis/
 
 linkcheck_allowed_redirects = {
     r'https://cdash\.org': r'https://www\.cdash\.org/',
+    r'https://cmake.org/get-involved/': r'https://cmake.org/documentation/',
     r'https://docs\.nvidia\.com/cuda/': r'https://docs\.nvidia\.com/cuda/index\.html',
     r'https://learn\.microsoft\.com/en-us/cpp/c-language/parsing-c-command-line-arguments': r'https://learn\.microsoft\.com/en-us/cpp/c-language/parsing-c-command-line-arguments\?.*',
     r'https://openjdk\.java\.net/jeps/313': r'https://openjdk\.org:443/jeps/313',