CODE_OF_CONDUCT.md: actually link to the CoC

Render the link as a clickable link instead of as code

Author: phw

CODE_OF_CONDUCT.md

@@ -8,7 +8,7 @@ MetaBrainz-sponsored projects.
 
 The full MetaBrainz Code of Conduct is found here:
 
-    https://metabrainz.org/code-of-conduct
+https://metabrainz.org/code-of-conduct
 
 For questions about the Code of Conduct or to get help, please email
 [email protected].