Warn when @author is missing.

[aubreypwd]

Resolves #5

TODO:

• Add the rest of the cases we would enforce this on

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What I've done is just required @author; due to the complexity of how we use this project to project I did not enforce a format. Also, just a warning and only enforced on functions and apply_filters/do_action.

[aubreypwd]

• Add ESLINT support

Though this will work on phpcs file.js, it won't work E.g. Sublime:

I imagine this is because sublime is running eslint and is overriding it?