Remove section on spring-framework-contrib group

CONTRIBUTING.md

@@ -33,14 +33,6 @@ do not find something similar, please create a new JIRA issue before submitting
 a pull request unless the change is truly trivial -- for example: typo fixes,
 removing compiler warnings, etc.
 
-### Discuss non-trivial contribution ideas with committers
-
-If you're considering anything more than correcting a typo or fixing a minor
-bug, please discuss it on the [spring-framework-contrib][] mailing list before
-submitting a pull request. We're happy to provide guidance, but please spend an
-hour or two researching the subject on your own, including searching the mailing
-list for prior discussions.
-
 ### Sign the Individual Contributor License Agreement (ICLA)
 
 If you have not previously done so, please fill out and submit the