Add api ref of 'get anomaly rule'

Add api ref of 'get anomaly rule'. The url of this api is v1/anomaly/rule/{id}.

Change-Id: If6688d0f8d3aecdbd586d5747cddd2a8bfb290c0

api-ref/source/v1/anomaly-detect.inc

@@ -5,6 +5,33 @@ Anomaly Detect
 
 Users can add, delete, modify and query anomaly rules, query and delete anomaly records.
 
+
+Get Anomaly Rule
+~~~~~~~~~~~~~~~~~~~
+
+.. rest_method:: GET /v1/anomaly/rule/{id}
+
+Get information of an anomaly rule.
+
+Request
+-------
+
+.. rest_parameters:: parameters.yaml
+
+   - id: rule_id
+
+Response codes
+--------------
+
+.. rest_status_code:: success ../status.yaml
+
+   - 1
+
+.. rest_status_code:: error ../status.yaml
+
+   - -1
+
+
 Get anomaly record
 ~~~~~~~~~~~~~~~~~~
 

api-ref/source/v1/parameters.yaml

@@ -81,6 +81,12 @@ request_id:
   in: query
   required: true
   type: string
+rule_id:
+  description: |
+    The id of an anomaly rule.
+  in: query
+  required: true
+  type: string
 start_time:
   description: |
     the start timestamp of time frame.