doc: update deprecations info in COLLABORATOR_GUIDE

The deprecations section in the COLLABORATOR_GUIDE is a bit long-winded
and repetitive. It also includes some aspirational items that appear
worded to create "an impression that a specific or meaningful statement
has been made, when instead only a vague or ambiguous claim has actually
been communicated." (Putting it in quotes because I'm copying it from
Wikipedia.)

This commit edits the text to make it more concise and meaningful.

Author: Trott

COLLABORATOR_GUIDE.md

@@ -463,11 +463,8 @@ Runtime Deprecation cycle. However, there is no requirement that deprecated
 code must progress ultimately to *End-of-Life*. Documentation-only and runtime
 deprecations may remain indefinitely.
 
-A best effort will be made to communicate pending deprecations and associated
-mitigations with the ecosystem as soon as possible (preferably before the pull
-request adding the deprecation lands on the master branch). All deprecations
-included in a Node.js release should be listed prominently in the "Notable
-Changes" section of the release notes.
+Use the `notable-change` label on all pull requests that add a new deprecation
+or move an existing deprecation to a new deprecation level.
 
 ### Involving the TSC