docs: update porting-to-0.11 document with a "soft" API changes checklist
docs: update porting-to-0.11 document with a "soft" API changes checklist

Point out some API changes that the compiler won't
be able to warn about.

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