docs: Move contributing files to root (#1044)

Author: deandreamatias

packages/form_builder_phone_field/example/CODE_OF_CONDUCT.md renamed to CODE_OF_CONDUCT.md

@@ -61,7 +61,7 @@ representative at an online or offline event.
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
 reported to the community leaders responsible for enforcement at
-[INSERT CONTACT METHOD].
+[Discord server](https://discord.gg/25KNPMJQf2).
 All complaints will be reviewed and investigated promptly and fairly.
 
 All community leaders are obligated to respect the privacy and security of the