manpages: fixed link to OSC interface desc in ecasound(1)
manpages: fixed link to OSC interface desc in ecasound(1)

jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2,jeremysalwen/Ecasound-LV2