update doc (#608)

* update doc

* update variable name

README.md

@@ -106,6 +106,8 @@ spec:
     generate:
       kind: ConfigMap
       name: zk-kafka-address
+      # create the resource in the new namespace
+      namespace: "{{request.object.name}}"
       data:
         kind: ConfigMap
         data:

documentation/writing-policies.md

@@ -76,7 +76,7 @@ spec :
       - key: name # compares (key operator value) 
         operator: Equal
         value: name # constant "name" == "name"
-      - key: "{{serviceAccount}}" # refer to a pre-defined variable serviceAccount
+      - key: "{{serviceAccountName}}" # refer to a pre-defined variable serviceAccountName
         operator: NotEqual
         value: "user1" # if service 
      # Each rule can contain a single validate, mutate, or generate directive