Clean up comment regexes

[winstliu]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions

Description of the Change

They were overly complicated and causing bugs such as https://github.com/atom/language-php/issues/187. Simplify them.

Alternate Designs

None.

Benefits

Easier to understand, less conflicts with other rules due to the removal of the ^ start-of-line match.

Possible Drawbacks

None.

Applicable Issues

Fixes atom/language-php#187

[Gonkers]

Fantastic! Thank you.