Adding docs about controlling http response status codes

[zhughes3]

References to other Issues or PRs

Adding notes to documentation after repeated discussion in #517 (comment)

Brief description of what is fixed or changed

Added documentation about controlling http response status codes.

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[zhughes3]

@googlebot I signed it!

[codecov-commenter]

Codecov Report

Merging #1391 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1391   +/-   ##
=======================================
  Coverage   54.14%   54.14%           
=======================================
  Files          42       42           
  Lines        4375     4375           
=======================================
  Hits         2369     2369           
  Misses       1750     1750           
  Partials      256      256           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5f308a6...321a5be. Read the comment docs.

[johanbrandhorst]

Hey, this looks great! Just a few nitpicky details:

• Could you unindent the code blocks to make it consistent with the rest of the file please?
• Looks like you've got too many tabs in the last snippet.

[johanbrandhorst]

@googlebot I signed it!

Try this without a quote

[googlebot]

CLAs look good, thanks!

ℹ️ Googlers: Go here for more info.

[johanbrandhorst]

Thanks for your contribution! Could you please cherry pick this against v2?

[zhughes3]

@johanbrandhorst Of course! I am trying to cherry pick it into the v2 branch. If you can be patient, my git-fu is still amateur at best.