Add @supportURL to scripts and styles

[rybak]

https://greasyfork.org/en/help/meta-keys#meta-supportURL

@supportURL
URL for a page where users can get support on a script (e.g. a bug tracker, a forum, an e-mail address). Support URL is displayed on a script's feedback page.

https://github.com/openstyles/stylus/wiki/Writing-UserCSS#supporturl

@supportURL

The URL the user can report issues to the UserCSS author. Displayed as "Feedback" link in the style's UserCSS configuration popup.

Example:

@supportURL https://github.com/octocat/Spoon-Knife/issues

[rybak]

Here's an example of how it looks for userstyles in Stylus. The link "Feedback" leads to https://github.com/rybak/atlassian-tweaks/issues.

[rybak]

Note: Tampermonkey automatically links to GitHub issues and to Greasy Fork's feedback page, when a script is installed via GitHub or Greasy Fork.