Part-of: <!330>

Víctor Manuel Jáquez Leal authored Apr 26, 2020 and GStreamer Marge Bot committed Apr 26, 2020

Part-of: <gstreamer/gstreamer-vaapi!320>

Veerabadhran Gopalakrishnan authored Apr 21, 2020 and Víctor Manuel Jáquez Leal committed Apr 21, 2020

Added the AMD hardware list to the "Hardware Requirements" section.

Update the URL where the release source tarballs can be downloaded.

The "Reporting bugs" section gives
https://bugzilla.gnome.org/enter_bug.cgi?product=gstreamer-vaapi

 as the
link to report a bug, but this link says "Sorry, entering a bug into the
product gstreamer-vaapi has been disabled.".

This commit fixes the URL to point to the proper location, and also
removes the following paragraph that is no longer correct.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

https://bugzilla.gnome.org/show_bug.cgi?id=779954

-- gitmodules: Change gstreamer-codecparsers submodule source download link
-- README: Change the gstreamer-vaapi webpage link

Drop references to deprecated plugins (vaapiupload, vaapidownload),
mention that support for GStreamer 0.10 is deprecated, make overview
more descriptive in certain aspects.

VA-API up to 0.34.0 is actually supported. Mention new video encoding
support. Update copyright years, list of supported Intel HD Graphics
hardware.

- GStreamer 1.2 APIs are supported ;
- Video Processing (VA/VPP) features.

Update build requirements for GStreamer 1.0.x support. Add section for
ways to report bugs.

Add vaapipostproc element for video postprocessing. So far, only basic
bob deinterlacing is implemented. Interlaced mode is automatically
detected based on sink caps ("interlaced" field).

Mention codecparsers-based decoders, FFmpeg is now optional. Update
list of support HW.