cogs.utils.github: Make complete [diff] clickable

[Vainock]

Description

This makes the complete [diff] clickable when someone edited a Wiki page, instead of just [diff.

Motivation and Context

It looks odd when only one bracket is highlighted.

How Has This Been Tested?

/

Types of changes

Tweak (non-breaking change to improve existing functionality)

Checklist:

• [x] My code has been run through clang-format.
• [x] I have read the contributing document.
• [x] My code is not on the master branch.
• [x] The code has been tested.
• [x] All commit messages are properly formatted and commits squashed where appropriate.
• [x] I have included updates to all appropriate documentation.

[derrod]

This is a rendering bug in the Android version of Discord. On Desktop it correctly renders like so: The brackets are intentionally not part of the link to distinguish them from the regular page link.

[Vainock]

That is really weird, thank you very much for clarification!