Document the negative commit message push rule for the API.

doc/api/projects.md

@@ -1631,6 +1631,7 @@ GET /projects/:id/push_rule
   "id": 1,
   "project_id": 3,
   "commit_message_regex": "Fixes \d+\..*",
+  "commit_message_negative_regex": "ssh\:\/\/",
   "branch_name_regex": "",
   "deny_delete_tag": false,
   "created_at": "2012-10-12T17:04:47Z",
@@ -1664,12 +1665,13 @@ POST /projects/:id/push_rule
 ```
 
 | Attribute                                     | Type           | Required | Description |
-| -------------------------------------- | -------------- | -------- | ----------- |
+| --------------------------------------------- | -------------- | -------- | ----------- |
 | `id`                                          | integer/string | yes      | The ID of the project or NAMESPACE/PROJECT_NAME |
 | `deny_delete_tag` **(STARTER)**               | boolean        | no       | Deny deleting a tag |
 | `member_check` **(STARTER)**                  | boolean        | no       | Restrict commits by author (email) to existing GitLab users |
 | `prevent_secrets` **(STARTER)**               | boolean        | no       | GitLab will reject any files that are likely to contain secrets |
 | `commit_message_regex` **(STARTER)**          | string         | no       | All commit messages must match this, e.g. `Fixed \d+\..*` |
+| `commit_message_negative_regex` **(STARTER)** | string         | no       | No commit message is allowed to match this, e.g. `ssh\:\/\/` |
 | `branch_name_regex` **(STARTER)**             | string         | no       | All branch names must match this, e.g. `(feature|hotfix)\/*` |
 | `author_email_regex` **(STARTER)**            | string         | no       | All commit author emails must match this, e.g. `@my-company.com$` |
 | `file_name_regex` **(STARTER)**               | string         | no       | All commited filenames must **not** match this, e.g. `(jar|exe)$` |
@@ -1685,12 +1687,13 @@ PUT /projects/:id/push_rule
 ```
 
 | Attribute                                     | Type           | Required | Description |
-| -------------------------------------- | -------------- | -------- | ----------- |
+| --------------------------------------------- | -------------- | -------- | ----------- |
 | `id`                                          | integer/string | yes      | The ID of the project or NAMESPACE/PROJECT_NAME |
 | `deny_delete_tag` **(STARTER)**               | boolean        | no       | Deny deleting a tag |
 | `member_check` **(STARTER)**                  | boolean        | no       | Restrict commits by author (email) to existing GitLab users |
 | `prevent_secrets` **(STARTER)**               | boolean        | no       | GitLab will reject any files that are likely to contain secrets |
 | `commit_message_regex` **(STARTER)**          | string         | no       | All commit messages must match this, e.g. `Fixed \d+\..*` |
+| `commit_message_negative_regex` **(STARTER)** | string         | no       | No commit message is allowed to match this, e.g. `ssh\:\/\/` |
 | `branch_name_regex` **(STARTER)**             | string         | no       | All branch names must match this, e.g. `(feature|hotfix)\/*` |
 | `author_email_regex` **(STARTER)**            | string         | no       | All commit author emails must match this, e.g. `@my-company.com$` |
 | `file_name_regex` **(STARTER)**               | string         | no       | All commited filenames must **not** match this, e.g. `(jar|exe)$` |