chore: use ! for breaking changes (#6994)

Signed-off-by: knqyf263 <[email protected]>

Author: knqyf263

.github/workflows/semantic-pr.yaml

@@ -29,7 +29,6 @@ jobs:
             chore
             revert
             release
-            BREAKING
 
           scopes: |
             vuln

docs/community/contribute/pr.md

@@ -185,12 +185,20 @@ others:
 
 The `<scope>` can be empty (e.g. if the change is a global or difficult to assign to a single component), in which case the parentheses are omitted.
 
+**Breaking changes**
+
+A PR, introducing a breaking API change, needs to append a `!` after the type/scope.
+
 ### Example titles
 
 ```
 feat(alma): add support for AlmaLinux
 ```
 
+```
+feat(vuln)!: delete the existing CLI flag
+```
+
 ```
 fix(oracle): handle advisories with ksplice versions
 ```