fix(doc): Remove new line in documentation comment

[adamread]

The newline in the comment caused a space in the generated documentation, breaking the link. Removing the newline should fix the link in the generated doc (see line 146 for an example of this already in the file).

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

Fixes #266

[tswast]

Thanks for the contribution! Unfortunately, since this is generated code our bot friend owlbot will immediately revert this change.

I looked at the source proto https://github.com/googleapis/googleapis/blob/e7aa1494257e326beb6798104fc6373d4c4fc4b8/google/cloud/bigquery/datatransfer/v1/transfer.proto#L137 which appears to be correct.

The problem must be with the generator. I've filed googleapis/gapic-generator-python#1131

[tswast]

Well, I triggered owlbot and it didn't revert the change as far as I can tell. Perhaps the generator is smart enough not to overwrite this?