Add some clarifications to usage message

Author: softins

src/main.cpp

@@ -1105,6 +1105,7 @@ QString UsageArguments ( char** argv )
            "                          (see the Jamulus website to enable QoS on Windows)\n"
            "  -t, --notranslation     disable translation (use English language)\n"
            "      --noipv6            disable IPv6 addressing (IPv4 is always enabled)\n"
+           "                          (recommended to leave IPv6 enabled by default)\n"
            "\n"
            "Server only:\n"
            "  -d, --discononquit      disconnect all Clients on quit\n"
@@ -1127,7 +1128,8 @@ QString UsageArguments ( char** argv )
            "      --norecord          set server not to record by default when recording is configured\n"
            "      --noraw             disable raw audio\n"
            "  -s, --server            start Server\n"
-           "      --serverbindip      IP address the Server will bind to (rather than all)\n"
+           "      --serverbindip      IPv4 address the Server will bind to (rather than all)\n"
+           "                          (only works if IPv6 is unavailable or disabled with --noipv6)\n"
            "  -T, --multithreading    use multithreading to make better use of\n"
            "                          multi-core CPUs and support more Clients\n"
            "  -u, --numchannels       maximum number of channels\n"