STYLE: add some comment, so it says at least a bit what it is good for

Alex

Modules/CMakeASM-ATTInformation.cmake

@@ -1,3 +1,5 @@
+# support for AT&T syntax assemblers, e.g. GNU as
+
 SET(ASM_DIALECT "-ATT")
 SET(CMAKE_ASM${ASM_DIALECT}_SOURCE_FILE_EXTENSIONS s;S;asm)
 INCLUDE(CMakeASMInformation)