Mentioned breaking change label in contribution guide

Clarifies documentaiton related to using "breaking change" label

Changelog: other

doc/development/contributing/issue_workflow.md

@@ -57,6 +57,10 @@ Most issues will have labels for at least one of the following:
 - Priority: `~"priority::1"`, `~"priority::2"`, `~"priority::3"`, `~"priority::4"`
 - Severity: ~`"severity::1"`, `~"severity::2"`, `~"severity::3"`, `~"severity::4"`
 
+Please add `~"breaking change"` label if the issue can be considered as a [breaking change](index.md#breaking-changes).
+
+Please add `~security` label if the issue is related to application security.
+
 All labels, their meaning and priority are defined on the
 [labels page](https://gitlab.com/gitlab-org/gitlab/-/labels).
 

doc/development/deprecation_guidelines/index.md

@@ -6,8 +6,8 @@ info: To determine the technical writer assigned to the Stage/Group associated w
 
 # Deprecation guidelines
 
-This page includes information about how and when to remove or make breaking
-changes to GitLab features.
+This page includes information about how and when to remove or make [breaking
+changes](../contributing/index.md#breaking-changes) to GitLab features.
 
 ## Terminology