gstcollectpads: Fix docs about GstCollectData list
gstcollectpads: Fix docs about GstCollectData list

Add to the docs the fact that is only safe to iterate
GstCollectPad's data list inside the collected callback.

Fixes #610366

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