how-to: query Redis store (#39)

* how-to: query Redis store

* Update query-redis-store.md

* Updates to the doc

howto/query-state-store/query-redis-store.md

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+# Query Redis state store
+
+Dapr doesn't transform state values while saving and retriving states. Dapr requires all state store implementations to abide by a certain key format scheme (see [Dapr state management spec](https://github.com/dapr/spec/blob/master/state.md)). You can directly interact with the underlying store to manipulate the state data, such querying states, creating aggregated views and making backups.
+
+>**NOTE:** The following examples uses Redis CLI against a Redis store using the default Dapr state store implementation. 
+
+## 1. List keys by Dapr id
+
+To get all state keys associated with application "myapp", use the command:
+
+```bash
+KEYS myapp*
+```
+
+The above command returns a list of existing keys, for example:
+```bash
+1) "myapp-balance"
+2) "myapp-amount"
+```
+
+## 2. Get specific state data
+
+Dapr saves state values as hash values. Each hash value contains a "data" field, which contains the state data and a "version" field, which contains an ever-incrementing version serving as the ETag.
+
+For example, to get the state data by a key "balance" for the application "myapp", use the command:
+
+```bash
+HGET myapp-balance data
+```
+
+To get the state version/ETag, use the command:
+```bash
+HGET myapp-balance version
+```
+## 3. Read actor state
+
+To get all the state keys associated with an actor with the instance ID "leroy" of actor type "cat" belonging to the application with ID "mypets", use the command:
+
+```bash
+KEYS mypets-cat-leroy*
+```
+And to get a specific actor state such as "food", use the command:
+
+```bash
+HGET mypets-cat-leroy-food value
+```
+
+> **WARNING:** You should not manually update or delete states in the store. All writes and delete operations should be done via the Dapr runtime.