There is no =head3. Convert to =head2.

llvm-svn: 21430
diff --git a/llvm/docs/CommandGuide/llvmc.pod b/llvm/docs/CommandGuide/llvmc.pod
index bc4d526..c8463c4 100644
--- a/llvm/docs/CommandGuide/llvmc.pod
+++ b/llvm/docs/CommandGuide/llvmc.pod
@@ -292,7 +292,7 @@
 
 =back
 
-=head3 C/C++ Specific Options
+=head2 C/C++ Specific Options
 
 =over