chore(docs): update helm install command (#703)

* Update README.md - Fix helm install command

The helm install command is missing the name parameter, so it does not work on helm 3.2.1 at least.

* Update helm commands in docs

Author: StianOvrevage

README.md

@@ -48,7 +48,7 @@ The official [helm chart](charts/kubernetes-external-secrets) can be used to cre
 
 ```bash
 $ helm repo add external-secrets https://external-secrets.github.io/kubernetes-external-secrets/
-$ helm install external-secrets/kubernetes-external-secrets
+$ helm install [RELEASE_NAME] external-secrets/kubernetes-external-secrets
 ```
 
 For more details about configuration see the [helm chart docs](charts/kubernetes-external-secrets/README.md)

charts/kubernetes-external-secrets/README.md

@@ -6,7 +6,7 @@
 
 ```bash
 $ helm repo add external-secrets https://external-secrets.github.io/kubernetes-external-secrets/
-$ helm install external-secrets/kubernetes-external-secrets
+$ helm install [RELEASE_NAME] external-secrets/kubernetes-external-secrets
 ```
 
 See below for [Helm V2 considerations](#helm-v2-considerations) when installing the chart.