Add comment regarding non-standard usage.
Add comment regarding non-standard usage.

matsu/gst-openmax,mrchapp/gst-openmax,mrchapp/gst-openmax,mrchapp/gst-openmax-devel,prajnashi/gst-openmax,PPCDroid/external-gst-openmax,felipec/gst-openmax,mrchapp/gst-openmax-devel,prajnashi/gst-openmax,PPCDroid/external-gst-openmax,freedesktop-unofficial-mirror/gstreamer__attic__gst-openmax,freedesktop-unofficial-mirror/gstreamer__attic__gst-openmax,mrchapp/gst-openmax-devel,matsu/gst-openmax,felipec/gst-openmax,mrchapp/gst-openmax