Help: Add notes for topic 'compiler-version-Fortran'

Help/release/dev/compiler-version-Fortran.rst

@@ -0,0 +1,6 @@
+compiler-version-Fortran
+------------------------
+
+* The version of some Fortran compilers is now detected and stored in the
+  :variable:`CMAKE_Fortran_COMPILER_VERSION <CMAKE_<LANG>_COMPILER_VERSION>`
+  variable.