Add `squash_commit_template` to API `edit project` documentation

doc/api/projects.md

@@ -1404,6 +1404,7 @@ Supported attributes:
 | `jobs_enabled`                                              | boolean        | **{dotted-circle}** No | _(Deprecated)_ Enable jobs for this project. Use `builds_access_level` instead. |
 | `lfs_enabled`                                               | boolean        | **{dotted-circle}** No | Enable LFS. |
 | `merge_commit_template`                                     | string         | **{dotted-circle}** No | [Template](../user/project/merge_requests/commit_templates.md) used to create merge commit message in merge requests. _([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/20263) in GitLab 14.5.)_ |
+| `squash_commit_template`                                    | string         | **{dotted-circle}** No | [Template](../user/project/merge_requests/commit_templates.md) used to create squash commit message in merge requests. _([Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/345275) in GitLab 14.6.)_ |
 | `merge_method`                                              | string         | **{dotted-circle}** No | Set the [merge method](#project-merge-method) used. |
 | `merge_requests_access_level`                               | string         | **{dotted-circle}** No | One of `disabled`, `private`, or `enabled`. |
 | `merge_requests_enabled`                                    | boolean        | **{dotted-circle}** No | _(Deprecated)_ Enable merge requests for this project. Use `merge_requests_access_level` instead. |