IVGCVSW-6777 Replace old Dockerfile with build-tool

* Removed old Dockerfile and associated docs.
* Keeping README as it currently ranks highly on
  web searches for "armnn docker" and providing
  a link to new alternative Arm NN Build Tool.

Change-Id: I0ce79cedffa035728e394c116912f36481804931
Signed-off-by: James Conroy <james.conroy@arm.com>

docker/README.md

@@ -1,29 +1,8 @@
 # ARMNN Docker Files
 
-## [ArmNN on x86_64 for arm64 and arm32](https://github.com/ARM-software/armnn/blob/branches/armnn_20_02/BuildGuideCrossCompilation.md)
-
-<b>x86_64</b> folder has the docker file to build ArmNN under an x86_64 system to target an Arm64 and Arm32 systems.
-
-# To build a docker images
-```bash
-docker build --rm --build-arg proxy=$http_proxy --rm --tag armnn:v1 .
-```
-
-# To Run docker images
-```bash
-docker run -v /etc/localtime:/etc/localtime:ro --rm -it -e http_proxy -e https_proxy -e ftp_proxy -v `pwd`:/work armnn:v1 bash
-```
-
-# To run a docker with X11 support for GUI Application
-```bash
-docker run -v /etc/localtime:/etc/localtime:ro --rm -it -e DISPLAY=$DISPLAY -v /tmp/.X11-unix:/tmp/.X11-unix -e http_proxy -e https_proxy -e ftp_proxy -v `pwd`:/work armnn:v1 bash
-```
-
-# To mount the camera and access camera from docker env
-```bash
-docker run -v /etc/localtime:/etc/localtime:ro --rm -it --device /dev/video0 -e http_proxy -e https_proxy -e ftp_proxy -v `pwd`:/work armnn:v1 bash
-```
+A productized Arm NN Docker solution has been released as part of our new Arm NN Build Tool which can be found at this link on our GitHub website: https://github.com/ARM-software/armnn/tree/HEAD/build-tool
 
+The above link automatically points to the latest release version of the Arm NN Build Tool and will be live when Arm NN 22.08 is released.