Help: Add link target to cmake-language.7 lists section

Help/manual/cmake-language.7.rst

@@ -538,6 +538,8 @@ The :manual:`cmake-variables(7)` manual documents many variables
 that are provided by CMake or have meaning to CMake when set
 by project code.
 
+.. _`CMake Language Lists`:
+
 Lists
 =====