fix a link

steveklabnik · steveklabnik · commit 1f95397a8127 · 2018-09-06T13:55:46.000-04:00
diff --git a/src/compatibility.md b/src/compatibility.md
@@ -4,4 +4,4 @@ The Rust language is fastly evolving, and because of this certain compatibility
 issues can arise, despite efforts to ensure forwards-compatibility wherever
 possible.
 
-* [Raw identifiers](compatibility/raw_identifiers.md)
+* [Raw identifiers](compatibility/raw_identifiers.html)
