docs: Modify docs string slightly.
docs: Modify docs string slightly.

Apparently starting the last line of a docs string with 'returns' both
confuses and enrages gtk-doc. Use a slightly different wording instead.

surround-io/gstreamer,centricular/gstreamer,mparis/gstreamer,justinjoy/gstreamer,mrchapp/gstreamer,ylatuya/gstreamer,krieger-od/gstreamer,shelsonjava/gstreamer,lubosz/gstreamer,magcius/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,cablelabs/gstreamer,justinjoy/gstreamer,lubosz/gstreamer,mrchapp/gstreamer,lovebug356/gstreamer,shelsonjava/gstreamer,Distrotech/gstreamer,jpxiong/gstreamer,ensonic/gstreamer,krieger-od/gstreamer,collects/gstreamer,lubosz/gstreamer,surround-io/gstreamer,krieger-od/gstreamer,mparis/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,justinjoy/gstreamer,jpxiong/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,cablelabs/gstreamer,drothlis/gstreamer,krichter722/gstreamer,surround-io/gstreamer,ahmedammar/platform_external_gst_gstreamer,collects/gstreamer,StreamUtils/gstreamer,mparis/gstreamer,jpakkane/gstreamer,ylatuya/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,cfoch/gstreamer,krichter722/gstreamer,lovebug356/gstreamer,mparis/gstreamer,centricular/gstreamer,cfoch/gstreamer,lovebug356/gstreamer,surround-io/gstreamer,ahmedammar/platform_external_gst_gstreamer,ylatuya/gstreamer,Lachann/gstreamer,centricular/gstreamer,drothlis/gstreamer,ensonic/gstreamer,krieger-od/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,Distrotech/gstreamer,Lachann/gstreamer,cfoch/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,jpakkane/gstreamer,justinjoy/gstreamer,Distrotech/gstreamer,magcius/gstreamer,ahmedammar/platform_external_gst_gstreamer,magcius/gstreamer,Distrotech/gstreamer,collects/gstreamer,ensonic/gstreamer,jpakkane/gstreamer,magcius/gstreamer,ylatuya/gstreamer,mrchapp/gstreamer,collects/gstreamer,centricular/gstreamer,krichter722/gstreamer,Lachann/gstreamer,krieger-od/gstreamer,collects/gstreamer,ylatuya/gstreamer,shelsonjava/gstreamer,drothlis/gstreamer,cablelabs/gstreamer,Distrotech/gstreamer,lovebug356/gstreamer,mrchapp/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,magcius/gstreamer,cfoch/gstreamer,mparis/gstreamer,Lachann/gstreamer,justinjoy/gstreamer,mrchapp/gstreamer,krichter722/gstreamer,lubosz/gstreamer,surround-io/gstreamer,lubosz/gstreamer,drothlis/gstreamer,ahmedammar/platform_external_gst_gstreamer,lovebug356/gstreamer,cfoch/gstreamer,drothlis/gstreamer,jpakkane/gstreamer,ahmedammar/platform_external_gst_gstreamer,ensonic/gstreamer