* snip.py: Replace github file token with release-specific URL.
* verify.sh: Show the expected output as well as the actual output.
* snip.py: Update the githubfile regex to not include email addresses.
When generating snip scripts, pairs of "@" signs indicate a link to
GitHub repo content. However, JWT attribute values contained pairs of
email addresses such as:
`testing@secure.istio.io/testing@secure.istio.io`
which would be treated as an email address and mangled. This commit
rewrites the regex to not match on email addresses.
* Add authz-jwt user guide test.