Add comment about keyshare negotiation

src/dtls.c

@@ -719,6 +719,7 @@ static int SendStatelessReplyDtls13(const WOLFSSL* ssl, WolfSSL_CH* ch)
                         "SupportedGroups.");
             ERROR_OUT(INCOMPLETE_DATA, dtls13_cleanup);
         }
+        /* TLSX_KeyShare_Choose is done deep inside MatchSuite_ex */
         ret = MatchSuite_ex(ssl, &suites, &cs, parsedExts);
         if (ret < 0) {
             WOLFSSL_MSG("Unsupported cipher suite, ClientHello");