Add TODO for now for handling multiple mentions

If it's just all mentions with no textual content = can close(?)
But if there're a lot of mentions, won't it be dangerous to close?
User can still edit whatever in between like rearranging the mentions etc

src/components/compose.jsx

@@ -271,6 +271,7 @@ function Compose({
     const isSelf = replyToStatus?.account.id === currentAccount;
     const hasOnlyAcct =
       replyToStatus && value.trim() === `@${replyToStatus.account.acct}`;
+    // TODO: check for mentions, or maybe just generic "@username<space>", including multiple mentions like "@username1<space>@username2<space>"
     if (!isSelf && hasOnlyAcct) {
       console.log('canClose', { isSelf, hasOnlyAcct });
       return true;