docs: Fix badge link to Code of Conduct

[greatislander]

Change Type

• [ ] Feature
• [x] Chore
• [ ] Bug Fix

Change Level

• [ ] major
• [ ] minor
• [x] patch

Further Information (screenshots, bug report links, etc.)

I noticed that the badge link to the Code of Conduct was broken. This PR fixes it.

Checklist

• [ ] Added tests / did not decrease code coverage
• [ ] Tested in supported environments (common browsers or current Node)

[zacanger]

Duplicate of #231