Add pragma to make it easier to find "image list" impl

I couldn't find it; make this easier for next time.

lldb/source/Commands/CommandObjectTarget.cpp

@@ -2834,6 +2834,7 @@ protected:
   OptionGroupUInt64 m_slide_option;
 };
 
+#pragma mark CommandObjectTargetModulesList
 // List images with associated information
 #define LLDB_OPTIONS_target_modules_list
 #include "CommandOptions.inc"