Update configuration doc to reflect tls_config in oauth2

[majolo]

Updated for this change: prometheus/common#331

Bringing in line with Prometheus docs: https://prometheus.io/docs/prometheus/latest/configuration/configuration/#oauth2

[gotjosh]

LGTM

[gotjosh]

@majolo can you please take care of the DCO?

[roidelapluie]

Thanks for your PR. For legal reasons, we require that all commits are signed with a DCO before we can merge them. See this blog post for considerations around this.

This means that the last line of your commit message should read like:

Signed-Off-By: Your Name <your@email.address>

If you are using GitHub through the web interface, it's quickest to close this PR and open a new one with the appropriate line.

If you are using Git on the command line, it is probably quickest to amend and force push. You can do that with

git commit --amend --signoff
git push -f $remote $remote_branch_for_pr

As always, be careful when force-pushing.

[majolo]

Thanks @roidelapluie @gotjosh, closing and opened this instead: #2947