Remove promises we cannot keep from CONTRIBUTING.md

Author: Photonios

CONTRIBUTING.md

@@ -17,10 +17,3 @@ If you're unsure whether your change would be a good fit for `django-postgres-ex
   * PEP8 passes.
 * Features that allow creating custom indexes or fields must also implement the associated migrations. `django-postgres-extra` prides itself on the fact that it integrates smoothly with Django migrations. We'd like to keep it that way for all features.
 * Sufficiently complicated changes must be accomponied by tests.
-
-## Our promise
-* We'll promise to reply to each pull request within 24 hours of submission.
-* We'll let you know whether we welcome the change or not within that timeframe.
-  * This avoids you wasting time on a feature that we feel is not a good fit.
-
-We feel that these promises are fair to whomever decides its worth spending their free time to contribute to `django-postgres-extra`. Please do let us know if you feel we are not living up to these promises.