[DOCS] Add sections to restart API page
Original commit: elastic/x-pack-elasticsearch@69fe367b39e4047d94f5d5475d0d16efc948a540
[[watcher-api-restart]]
=== Restart API
-The `restart` API stops, then starts the {watcher} service, as in the
-following example:
+The `restart` API stops then starts the {watcher} service.
+
+
+[float]
+==== Request
+
+`POST _xpack/watcher/_restart`
+
+
+[float]
+==== Authorization
+
+You must have `manage_watcher` cluster privileges to use this API. For more
+information, see {xpack-ref}/security-privileges.html[Security Privileges].
+
+
+[float]
+==== Examples
[source,js]
--------------------------------------------------
