Fix docstring syntax errors

[mthuurne]

This removes some noise from the pydoctor logging, so actual problems will stand out more.

Contributor Checklist:

• The associated ticket in Trac is here: https://twistedmatrix.com/trac/ticket/9868
• The changes pass minimal style checks (see: https://twistedmatrix.com/trac/wiki/TwistedDevelopment#GettingYourPatchAccepted )
• I have created a newsfragment in src/twisted/newsfragments/ (see: https://twistedmatrix.com/trac/wiki/ReviewProcess#Newsfiles )
• I have updated the automated tests. Only docstrings are changed.
• I have submitted the associated Trac ticket for review by adding the word review to the keywords field in Trac, and putting a link to this PR in the comment; it shows up in https://twisted.reviews/ now.

[mthuurne]

CircleCI refuses to let me view the details of the test failure unless I hand it read/write access to all my repositories, which I'm obviously not going to agree to. Is this a bug? If not, I think it's a completely unacceptable policy, both in terms of privacy and security.

Update: exarkun was kind enough to copy-paste the error message on IRC; it was about the missing news fragment. I still think it's a problem though that CircleCI won't show details unless you hand it a bunch of permissions it doesn't need.

[mthuurne]

The problem identified by Travis is the one I mentioned in the initial comment: lint errors near, but not caused by, the changed lines. Should I fix those even though they have nothing to do with the actual purpose of the PR?

I fixed the unrelated lint errors in a separate commit.

[rodrigc]

This looks OK

[rodrigc]

@mthuurne in future when you merge your PR to Twisted's trunk, you need to manually add these three lines to the merge commit message:

Author:
Reviewer:
Fixes: ticket:

This auto-closes the Trac ticket, and updates https://twistedmatrix.com/highscores

See: https://twistedmatrix.com/trac/wiki/ReviewProcess#Authors:Howtomergethechangetotrunk

You can also look at some other merge commits in Twisted for examples.

[mthuurne]

Sorry, this was my first time merging a commit for Twisted; I'll do that next time.

[rodrigc]

It's OK, the Twisted dev process is a bit complicated for newcomers, but once you get the hang of it, it is OK.