update secrets docs (#443)

* update secrets docs

* Update gcp-secret-manager.md

* Update hashicorp-vault.md

* Update component-secrets.md

howto/setup-secret-store/azure-keyvault.md

@@ -160,6 +160,7 @@ spec:
   - name: redisPassword
     secretKeyRef:
       name: redisPassword
+      key: redisPassword
 auth:
     secretStore: azurekeyvault
 ```
@@ -257,6 +258,7 @@ spec:
   - name: redisPassword
     secretKeyRef:
       name: redisPassword
+      key: redisPassword
 auth:
     secretStore: azurekeyvault
 ```

howto/setup-secret-store/gcp-secret-manager.md

@@ -49,6 +49,7 @@ When running in self hosted mode, place this file in a `components` directory un
 ## GCP Secret Manager reference example
 
 This example shows you how to take the Redis password from the GCP Secret Manager secret store.
+Here, you created a secret named `redisPassword` in GCP Secret Manager. Note its important to set it both as the `name` and `key` properties.
 
 ```yaml
 apiVersion: dapr.io/v1alpha1
@@ -63,6 +64,7 @@ spec:
   - name: redisPassword
     secretKeyRef:
       name: redisPassword
+      key: redisPassword
 auth:
     secretStore: gcpsecretmanager
 ```

howto/setup-secret-store/hashicorp-vault.md

@@ -61,6 +61,7 @@ spec:
   - name: redisPassword
     secretKeyRef:
       name: redisPassword
+      key: redisPassword
 auth:
     secretStore: vault
 ```