(fix): typo in docs (#470)

fixes grammatical mistake in onboarding docs

docs/user-guides/cluster/onboarding.md

@@ -16,7 +16,7 @@ NOTE: The UI is currently in development. For now this guide describes the onboa
 
 ### Preparation
 
-Download the latest `greenhousectl` binary for from [here](https://github.com/cloudoperators/greenhouse/releases). 
+Download the latest `greenhousectl` binary from [here](https://github.com/cloudoperators/greenhouse/releases). 
 
 The command line tool requires access to both the Greenhouse **and** your Kubernetes cluster. 
 Hence, have the `kubeconfig` files for both clusters at hand. The `kubeconfig` file for the Greenhouse Kubernetes cluster can be downloaded via the Greenhouse dashboard: _Organization_ > _Clusters_ > _Access greenhouse cluster_. 
@@ -85,4 +85,4 @@ When the `status.kubernetesVersion` field shows the correct version of the Kuber
 In the remote cluster, a new namespace is created and contains some resources managed by Greenhouse. 
 The namespace has the same name as your organization in Greenhouse. 
 
-If the bootstrapping failed, you can delete the Kubernetes cluster from Greenhouse with `kubectl --namespace=<greenhouse-organization-name> delete cluster <name>` and run the bootstrap command again.
+If the bootstrapping failed, you can delete the Kubernetes cluster from Greenhouse with `kubectl --namespace=<greenhouse-organization-name> delete cluster <name>` and run the bootstrap command again.