The most likely documentation page a project author will read in
response to a policy warning is the page for the policy itself.
Add to every policy documentation page a note explicitly stating
that the OLD behavior is deprecated. Also mention this in the
cmake_policy() command documentation that explains how to set a
policy to OLD.
Suggested-by: Fraser Hutchison <fraser.hutchison@gmail.com>
This is the convention suggested in the Sphinx documentation and is
already used in several other places in the CMake documentation.
Update a few places where we were using other characters.
Note in a few places of the cmake_policy() command documentation
that the cmake_minimum_required() command can set policies too.
Inspired-by: Peter Kümmel <syntheticpp@gmx.net>
