Update CI API documentation for runners

[ci skip]

doc/ci/api/runners.md

 # Runners API
 
+API used by runners to register and delete itselves.
+
 _**Note:** This API is intended to be used only by Runners as their own
 communication channel. For the consumer API see the
 [new Runners API](../../api/runners.md)._
 
 ## Runners
 
-### Retrieve all runners
-
-__Authentication is done by GitLab user token & GitLab url__
-
-Used to get information about all runners registered on the GitLab CI
-instance.
-
-    GET /ci/runners
-
-Returns:
-
-```json
-[
-  {
-    "id" : 85,
-    "token" : "12b68e90394084703135"
-  },
-  {
-    "id" : 86,
-    "token" : "76bf894e969364709864"
-  },
-]
-```
-
 ### Register a new runner
 
-
-__Authentication is done with a Shared runner registration token or a project Specific runner registration token__
+__Authentication is done with a shared runner registration token or a project
+specific runner registration token.__
 
 Used to make GitLab CI aware of available runners.
 
-    POST /ci/runners/register
+    POST /runners/register
 
 Parameters:
 
-  * `token` (required) - The registration token. It is 2 types of token you can pass here. 
+  * `token` (required) - The registration token.
+
+It is 2 types of token you can pass here.
 
 1. Shared runner registration token
 2. Project specific registration token
 
-Returns:
-
-```json
-{
-  "id" : 85,
-  "token" : "12b68e90394084703135"
-}
-```
-
 ### Delete a runner
 
+__Authentication is done by using runner token.__
 
-__Authentication is done by runner token__
-
-Used to removing runners.
+Used to remove runner.
 
-    DELETE /ci/runners/delete
+    DELETE /runners/delete
 
 Parameters:
 
   * `token` (required) - The runner token.
-
-Returns:
-
-```json
-{
-  "id" : 1,
-  "token" : "d14963981a428f70121777e50643d1",
-  "created_at" : "2015-02-26T11:39:39.232Z",
-  "updated_at" : "2015-02-26T11:39:39.232Z",
-  "description" : "awesome runner"
-}
-```