Adding Secure File size upload limit to API docs

doc/api/secure_files.md

@@ -11,7 +11,7 @@ type: reference, api
 
 FLAG:
 On self-managed GitLab, by default this feature is not available. To make it available,
-ask an administrator to [enable the feature flag](../administration/feature_flags.md) named `ci_secure_files`. Limited to 100 secure files per project. The feature is not ready for production use. 
+ask an administrator to [enable the feature flag](../administration/feature_flags.md) named `ci_secure_files`. Limited to 100 secure files per project. Files must be smaller than 5 MB. The feature is not ready for production use. 
 
 ## List project secure files
 
@@ -104,7 +104,7 @@ Supported attributes:
 |-----------------|----------------|------------------------|-------------|
 | `project_id`    | integer/string | **{check-circle}** Yes | The ID or [URL-encoded path of the project](index.md#namespaced-path-encoding) owned by the authenticated user. |
 | `name`          | string         | **{check-circle}** Yes | The `name` of the file being uploaded. |
-| `file`          | file           | **{check-circle}** Yes | The `file` being uploaded. |
+| `file`          | file           | **{check-circle}** Yes | The `file` being uploaded (5 MB limit). |
 | `file_checksum` | file           | **{dotted-circle}** No | An optional sha256 checksum of the file to be uploaded. If provided, the checksum must match the uploaded file, or the upload will fail to validate. [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/355653) in GitLab 14.10. |
 | `permissions`   | string         | **{dotted-circle}** No | The file is created with the specified permissions when created in the CI/CD job. Available types are: `read_only` (default), `read_write`, and `execute`. |