[stable-2.20] regex: fix example documentation for regex_test (#86172) (#86256)

Fixes: https://github.com/ansible/ansible-documentation/issues/3246
(cherry picked from commit 5f2d96c)

Signed-off-by: Abhijeet Kasurde <Akasurde@redhat.com>

lib/ansible/plugins/test/regex.yml

@@ -28,7 +28,7 @@ DOCUMENTATION:
       choices: [match, search, fullmatch]
       default: search
 
-EXAMPLES:
+EXAMPLES: |
   - name: check if string matches regex
     assert:
       that: