Coding Standards Updates Mega Issue

We currently exclude quite a few coding standards rules. Most of these rules are related to docblock and comment styling. Some require updates to code and tests. This issue is a mega issue to track all of the updates that should be made.

To see files that need updates, check the [phpcs.xml](https://github.com/gocodebox/lifterlms/blob/master/phpcs.xml) file and delete/comment out the corresponding rule. Then run `composer run-script check-cs-errors`.

When submitting pull requests to work on parts of this issue please submit PRs for no more than 15 files per PR. That means if you wish to update 100 files you'll need to submit 7 different PRs.

In the PR please Add `Per #946` to the PR description to reference (but not close) this issue.

When making updates please adhere to our [coding](https://github.com/gocodebox/lifterlms/blob/master/docs/coding-standards.md) and [documentation](https://github.com/gocodebox/lifterlms/blob/master/docs/documentation-standards.md) standards.

- [ ] Add translation placeholder comments, currently excluded by ``
- [ ] Inline parameter comments should end in a full stop, excluded by ``
- [ ] Function parameter comments should end in a full stop, excluded by ``
- [ ] Coment descriptions should start with a capital letter: `` and ``

- [ ] File header comments should obey [documentation standards](https://github.com/gocodebox/lifterlms/blob/master/docs/documentation-standards.md#file-headers-1):
``
``
``
``
``
``
``
``
``
``
``
``

- [ ] Function and method comments should obey [documentation standards](https://github.com/gocodebox/lifterlms/blob/master/docs/documentation-standards.md#functions-and-class-methods):
``
``
``
``
``
``

- [x] `` Fixed in #1321

Start with phpcs.xml and the listed excluded rules, then run composer run-script check-cs-errors to identify affected files. Read docs/coding-standards.md and docs/documentation-standards.md before updating a focused group of no more than 15 files; done means that group complies with the relevant checks and is submitted as a PR referencing #946.

Written by the indexing model from the issue text.