docs: Clarify note on local provisioners

Author: jen20

website/source/docs/provisioners/local-exec.html.markdown

@@ -13,8 +13,9 @@ is created. This invokes a process on the machine running Terraform, not on
 the resource. See the `remote-exec` [provisioner](/docs/provisioners/remote-exec.html)
 to run commands on the resource.
 
-Beware that even though the resource is fully created when the provisioner is run,
-it doesn't need to have finished booting or starting system services.
+Note that even though the resource will be ifully created when the provisioner is run,
+there is no guarantee that it will be in an operable state - for example system services
+such as `sshd` may not be started yet on compute resources.
 
 ## Example usage