Add documentation for feature and API

doc/api/project_aliases.md

+# Project Aliases API
+
+All methods require administrator authorization.
+
+## List all project aliases
+
+Get a list of all project aliases
+
+```
+GET /project_aliases
+```
+
+```
+curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/project_aliases"
+```
+
+Example response:
+
+```json
+[
+  {
+    "id": 1,
+    "project_id": 1,
+    "name": "gitlab-ce"
+  },
+  {
+    "id": 2,
+    "project_id": 2,
+    "name": "gitlab-ee"
+  }
+]
+```
+
+## Get project alias' details
+
+Get details of a project alias
+
+```
+GET /project_aliases/:name
+```
+
+| Attribute | Type   | Required | Description           |
+|-----------|--------|----------|-----------------------|
+| `name`    | string | yes      | The name of the alias |
+
+```
+curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/project_aliases/gitlab-ee"
+```
+
+Example response:
+
+```json
+{
+  "id": 1,
+  "project_id": 1,
+  "name": "gitlab-ee"
+}
+```
+
+## Create an alias for a project
+
+Add a new alias for a project. Reponds with a 201 when successful, 400 when there are validation errors (e.g. alias already exists).
+
+```
+POST /project_aliases
+```
+
+| Attribute    | Type   | Required | Description                                   |
+|--------------|--------|----------|-----------------------------------------------|
+| `project_id` | string | yes      | The The ID or URL-encoded path of the project |
+| `name`       | string | yes      | The name of the alias. Must be unique.        |
+
+```
+curl --request POST "https://gitlab.example.com/api/v4/project_aliases" --form "project_id=gitlab-org%2Fgitlab-ee" --form "name=gitlab-ee"
+```
+
+Example response:
+
+```json
+{
+  "id": 1,
+  "project_id": 1,
+  "name": "gitlab-ee"
+}
+```
+
+## Delete a project aliase
+
+Removes a project aliases. Respond with a 204 when project alias exists, 404 when it doesn't.
+
+```
+DELETE /project_aliases/:name
+```
+
+| Attribute | Type   | Required | Description           |
+|-----------|--------|----------|-----------------------|
+| `name`    | string | yes      | The name of the alias |
+
+```
+curl --request DELETE --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/project_aliases/gitlab-ee"
+```

doc/user/project/index.md

@@ -193,6 +193,18 @@ password <personal_access_token>
 To quickly access a project from the GitLab UI using the project ID,
 visit the `/projects/:id` URL in your browser or other tool accessing the project.
 
+## Project aliases
+
+Projects' repositories are usually cloned with a namespace and project name. It is
+also possible to clone them via a project alias. This feature is only available on Git over SSH.
+
+A project alias can be created via API only by administrators. Follow the
+[Project Aliases API documentation](../../api/project_aliases.md) for more details.
+
+Once an alias has been created for a project (e.g. gitlab-ce for gitlab-org/gitlab-ce),
+the repository can be cloned using the alias (e.g `git clone git@gitlab.com:gitlab-ce.git`
+instead of `git clone git@gitlab.com:gitlab-org/gitlab-ce.git`).
+
 ## Project APIs
 
 There are numerous [APIs](../../api/README.md) to use with your projects:
@@ -212,3 +224,4 @@ There are numerous [APIs](../../api/README.md) to use with your projects:
 - [Templates](../../api/project_templates.md)
 - [Traffic](../../api/project_statistics.md)
 - [Variables](../../api/project_level_variables.md)
+- [Aliases](../../api/project_aliases.md)