Make it easier to execute commands in the release notes

[thewtex]

In the release documentation, ITK/Documentation/Release.md make it easier to copy and execute commands.

• Remove $ from shell commands
• For long, multi-line commands, create short scripts inline, e.g.

cat << REMOTE_SCRIPT_EOF > /tmp/itk_linux_release.sh
set -ex

cd ~/Packaging/ITKPythonPackage
git reset --hard HEAD
git fetch origin
git checkout v$version
git clean -fdx
/home/kitware/Support/skbuild-venv/bin/python setup.py sdist --formats=gztar,zip
./scripts/dockcross-manylinux-build-wheels.sh
tar cvzf /tmp/dist-linux.tar.gz ./dist
rm dist/*
cd ..
./ITKPythonPackage/scripts/dockcross-manylinux-build-tarball.sh

REMOTE_SCRIPT_EOF

ssh $metroplex 'bash -s' < /tmp/itk_linux_release.sh

Suggested by @jcfr

See also the discussion here:

http://review.source.kitware.com/#/c/23699/

[jcfr]

Similarly, set of commands could be listed as:

   $ git checkout release && \
     git reset --hard origin/release && \
     git merge --ff-only v$version && \
     git push origin release && \
     git checkout master

instead of

   $ git checkout release
   $ git reset --hard origin/release
   $ git merge --ff-only v$version
   $ git push origin release
   $ git checkout master

It allows to copy paste the whole block

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[thewtex]

We will still shoot for this in the ITK 5 release.