Documentation cleanup: escaped a < character in a Doxygen comment.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158631 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index e780c66..40129c2 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -1659,7 +1659,7 @@
   const ArrayType *getAsArrayTypeUnsafe() const;
 
   /// Member-template castAs<specific type>.  Look through sugar for
-  /// the underlying instance of <specific type>.
+  /// the underlying instance of \<specific type>.
   ///
   /// This method has the same relationship to getAs<T> as cast<T> has
   /// to dyn_cast<T>; which is to say, the underlying type *must*