Add help text to "environment scope" field in new cluster form

app/views/clusters/clusters/gcp/_form.html.haml

@@ -17,9 +17,11 @@
   .form-group
     = field.label :name, s_('ClusterIntegration|Kubernetes cluster name'), class: 'label-bold'
     = field.text_field :name, class: 'form-control', placeholder: s_('ClusterIntegration|Kubernetes cluster name')
+  - if has_multiple_clusters?
     .form-group
       = field.label :environment_scope, s_('ClusterIntegration|Environment scope'), class: 'label-bold'
-    = field.text_field :environment_scope, class: 'form-control', readonly: !has_multiple_clusters?, placeholder: s_('ClusterIntegration|Environment scope')
+      = field.text_field :environment_scope, class: 'form-control', placeholder: s_('ClusterIntegration|Environment scope')
+      .form-text.text-muted= s_("ClusterIntegration|Choose which of your environments will use this cluster.")
 
   = field.fields_for :provider_gcp, @gcp_cluster.provider_gcp do |provider_gcp_field|
     .form-group

app/views/clusters/clusters/user/_form.html.haml

@@ -7,6 +7,7 @@
     .form-group
       = field.label :environment_scope, s_('ClusterIntegration|Environment scope'), class: 'label-bold'
       = field.text_field :environment_scope, class: 'form-control', placeholder: s_('ClusterIntegration|Environment scope')
+      .form-text.text-muted= s_("ClusterIntegration|Choose which of your environments will use this cluster.")
 
   = field.fields_for :platform_kubernetes, @user_cluster.platform_kubernetes do |platform_kubernetes_field|
     .form-group