Add note about alternative to opacity

src/components/views/messages/SenderProfile.js

@@ -56,6 +56,7 @@ export default function SenderProfile(props) {
             // It is not possible to wrap the whole thing, because the user name might contain flair which should
             // be shown at full opacity. Sadly CSS does not make it possible to "reset" opacity so we have to do it
             // in parts like this. Sometimes CSS makes me a sad panda :-(
+            // XXX: This could be avoided if the actual colour is set, rather than faking it with opacity
             { content.props.children[0] ?
                 <span className='mx_SenderProfile_aux'>{ content.props.children[0] }</span> : ''
             }