docs: mention more api changes in the porting guide
docs: mention more api changes in the porting guide

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