Merge branch 'docs-nfriend-clarify-ref-required' into 'master'

Clarify the conditions in which `ref` is required

See merge request gitlab-org/gitlab!18127

doc/api/releases/index.md

@@ -306,7 +306,7 @@ POST /projects/:id/releases
 | `name`             | string          | yes                         | The release name.                                                                                                                |
 | `tag_name`         | string          | yes                         | The tag where the release will be created from.                                                                                  |
 | `description`      | string          | yes                         | The description of the release. You can use [markdown](../../user/markdown.md).                                                  |
-| `ref`              | string          | no       | If `tag_name` doesn't exist, the release will be created from `ref`. It can be a commit SHA, another tag name, or a branch name. |
+| `ref`              | string          | yes, if `tag_name` doesn't exist | If `tag_name` doesn't exist, the release will be created from `ref`. It can be a commit SHA, another tag name, or a branch name. |
 | `milestones`       | array of string | no                          | The title of each milestone the release is associated with.                                                                      |
 | `assets:links`     | array of hash   | no                          | An array of assets links.                                                                                                        |
 | `assets:links:name`| string          | required by: `assets:links` | The name of the link.                                                                                                            |