Code of conduct moved to ruby-grape.org. [ci skip]

Author: dblock

CHANGELOG.md

@@ -14,7 +14,6 @@
 * [#1167](https://github.com/ruby-grape/grape/pull/1167): Refactor and extend coercion and type validation system - [@dslh](https://github.com/dslh).
 * [#1163](https://github.com/ruby-grape/grape/pull/1163): First-class `JSON` parameter type - [@dslh](https://github.com/dslh).
 * [#1161](https://github.com/ruby-grape/grape/pull/1161): Custom parameter coercion using `coerce_with` - [@dslh](https://github.com/dslh).
-* [#1134](https://github.com/ruby-grape/grape/pull/1134): Adds a code of conduct - [@towanda](https://github.com/towanda).
 
 #### Fixes