tools: minor addition to gst-launch-1.0 man page
tools: minor addition to gst-launch-1.0 man page

https://bugzilla.gnome.org/show_bug.cgi?id=692015

Lachann/gstreamer,shelsonjava/gstreamer,StreamUtils/gstreamer,StreamUtils/gstreamer,ensonic/gstreamer,ensonic/gstreamer,surround-io/gstreamer,jpakkane/gstreamer,lubosz/gstreamer,krichter722/gstreamer,krieger-od/gstreamer,krieger-od/gstreamer,lovebug356/gstreamer,krieger-od/gstreamer,cablelabs/gstreamer,cablelabs/gstreamer,StreamUtils/gstreamer,justinjoy/gstreamer,shelsonjava/gstreamer,shelsonjava/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,centricular/gstreamer,justinjoy/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,lubosz/gstreamer,cfoch/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,mparis/gstreamer,ensonic/gstreamer,lubosz/gstreamer,StreamUtils/gstreamer,cfoch/gstreamer,lubosz/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,justinjoy/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,collects/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,lovebug356/gstreamer,ensonic/gstreamer,lubosz/gstreamer,Lachann/gstreamer,cfoch/gstreamer,ensonic/gstreamer,krieger-od/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,justinjoy/gstreamer,cablelabs/gstreamer,collects/gstreamer,lovebug356/gstreamer,collects/gstreamer,mparis/gstreamer,jpxiong/gstreamer,krieger-od/gstreamer,surround-io/gstreamer,krichter722/gstreamer,Lachann/gstreamer,mparis/gstreamer,jpxiong/gstreamer,jpakkane/gstreamer,cfoch/gstreamer,collects/gstreamer,krichter722/gstreamer,cfoch/gstreamer,krichter722/gstreamer,cablelabs/gstreamer,centricular/gstreamer,lovebug356/gstreamer,collects/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,justinjoy/gstreamer,jpakkane/gstreamer,krichter722/gstreamer,mparis/gstreamer,mparis/gstreamer,lovebug356/gstreamer,centricular/gstreamer