caps: update docs, is_subset() works now
caps: update docs, is_subset() works now

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