Merge branch '221184-rolling-28-day-snippets-documentation' into 'master'

Doc for rolling 28 day  snippets counter

Closes #221184

See merge request gitlab-org/gitlab!34919

doc/development/telemetry/usage_ping.md

@@ -461,7 +461,8 @@ appear to be associated to any of the services running, since they all appear to
 | `releases`                                                | `counts`                             | `release`     |                  |         | Unique release tags                                                        |
 | `remote_mirrors`                                          | `counts`                             |               |                  |         |                                                                            |
 | `requirements_created`                                    | `counts`                             |               |                  |         |                                                                            |
-| `snippets`                                                | `counts`                             |               |                  |         |                                                                            |
+| `snippets`                                                | `counts`                             |  'create'     |                  |         |                                                                            |
+| `snippets`                                                | `counts_monthly`                     |  'create'     |                  |         |                                                                            |
 | `suggestions`                                             | `counts`                             |               |                  |         |                                                                            |
 | `todos`                                                   | `counts`                             |               |                  |         |                                                                            |
 | `uploads`                                                 | `counts`                             |               |                  |         |                                                                            |