Utilities/Sphinx: Add role and directive for 'genex' in CMake domain

This enables cross-reference syntax for CMake generator expressions:

    :genex:`SOME_GENEX`
    :genex:`$<SOME_GENEX>`
    :genex:`$<SOME_GENEX:...>`

and definition of CMake generator expressions via a directive:

    .. genex:: SOME_GENEX
    .. genex:: $<SOME_GENEX>
    .. genex:: $<SOME_GENEX:...>

It also adds generator expressions defined by the directive and by
`Help/genex/SOME_GENEX.rst` documents to the index.

1 files changed, 1 insertions, 0 deletions

diff --git a/Utilities/Sphinx/create_identifiers.py b/Utilities/Sphinx/create_identifiers.py
index e35f127701..0ff39a0c2a 100755
--- a/Utilities/Sphinx/create_identifiers.py
+++ b/Utilities/Sphinx/create_identifiers.py
@@ -25,6 +25,7 @@ for line in lines:
              ("envvar", "envvar"),
              ("variable", "variable"),
              ("generator", "generator"),
+             ("genex", "genex"),
              ("guide", "guide"),
              ("target property", "prop_tgt"),
              ("test property", "prop_test"),