Added description to modules/mod-cfg-multiple-targets.rs

Author: spencer3035

tests/ui/modules/mod-cfg-multiple-targets.rs

@@ -1,7 +1,24 @@
 //@ run-pass
 
-// Regression test for a problem with the first mod attribute
-// being applied to every mod
+//! This test was to solve a bug as the rust notation for attributes on modules was transitioning
+//! from
+//!
+//! ```
+//! mod foo = "foo.rs";
+//! ```
+//!
+//! to
+//!
+//! ```
+//! #[path = "foo.rs"]
+//! mod foo;
+//! ```
+//!
+//! This specifically was testing when an attribute was being applied to all modules instead of the
+//! first one
+//!
+//! Added in commit: https://github.com/rust-lang/rust/commit/7aee9f7b56f8d96f9444ebb1d06e32e024b81974
+//! Issue : https://github.com/rust-lang/rust/issues/906
 
 #[cfg(target_os = "linux")]
 mod hello {}