Delete stale packaging scripts (#5433) (#5437)

* Delete stale packaging scripts

`osx_wheel.sh` and `linux_manywheel.sh` has not been functional for a
while and are not referenced from any of the CI scripts

Updated `README.md` to reflect how release binary builds are currently run

Co-authored-by: Nikita Shulga <nshulga@fb.com>

packaging/README.md

@@ -1,90 +1,6 @@
 # Building torchvision packages for release
 
-## Anaconda packages
+TorchVision release packages are built by using `build_wheel.sh` and `build_conda.sh` for all permutations of
+supported operating systems, compute platforms and python versions.
 
-### Linux
-
-```bash
-nvidia-docker run -it --ipc=host --rm -v $(pwd):/remote soumith/conda-cuda bash
-pushd remote/conda
-
-./build_vision.sh 9.0
-./build_vision.sh 10.0
-./build_vision.sh cpu
-
-# copy packages over to /remote
-# exit docker
-# anaconda upload -u pytorch torchvision*.bz2
-```
-
-### OSX
-
-```bash
-# create a fresh anaconda environment / install and activate it
-conda install -y conda-build anaconda-client
-./build_vision.sh cpu
-
-# copy packages over to /remote
-# exit docker
-# anaconda upload -u pytorch torchvision*.bz2
-```
-
-### Windows
-
-```bash
-# Open `Git Bash` and change dir to `conda`
-./build_vision.sh 9.0
-./build_vision.sh 10.0
-./build_vision.sh cpu
-
-# copy packages to a output directory
-# anaconda upload -u pytorch torchvision*.bz2
-```
-
-## Wheels
-
-### Linux
-
-pushd wheel
-
-```bash
-nvidia-docker run -it --ipc=host --rm -v $(pwd):/remote soumith/manylinux-cuda90:latest bash
-cd remote
-./linux_manywheel.sh cu90
-
-rm -rf /usr/local/cuda*
-./linux_manywheel.sh cpu
-```
-
-```bash
-nvidia-docker run -it --ipc=host --rm -v $(pwd):/remote soumith/manylinux-cuda100:latest bash
-cd remote
-./linux_manywheel.sh cu100
-```
-
-wheels are in the folders `cpu`, `cu90`, `cu100`.
-
-You can upload the `cu90` wheels to twine with `twine upload *.whl`.
-Which wheels we upload depends on which wheels PyTorch uploads as default, and right now, it's `cu90`.
-
-### OSX
-
-```bash
-pushd wheel
-./osx_wheel.sh
-```
-
-### Windows
-
-```cmd
-set PYTORCH_REPO=pytorch
-
-pushd windows
-call build_vision.bat 90 0.3.0 1
-call build_vision.bat 100 0.3.0 1
-call build_vision.bat cpu 0.3.0 1
-```
-
-wheels are in the current folder.
-
-You can upload them to twine with `twine upload *.whl`
+OS/Python/Compute matrix is defined in https://github.com/pytorch/vision/blob/main/.circleci/regenerate.py