Use dashes not underscores for linode labels. (ansible#44719)

This is because underscores are illegals in hostnames and users might
want to create the same host names are the name of the Linode machine
(as in the report in ansible#30059).

Closes ansible#30059.

lib/ansible/modules/cloud/linode/linode.py

@@ -29,7 +29,7 @@
   name:
     description:
      - Name to give the instance (alphanumeric, dashes, underscore).
-     - To keep sanity on the Linode Web Console, name is prepended with C(LinodeID_).
+     - To keep sanity on the Linode Web Console, name is prepended with C(LinodeID-).
     required: true
   displaygroup:
     description:
@@ -367,7 +367,7 @@ def linodeServers(module, api, state, name,
                                         PaymentTerm=payment_term)
                 linode_id = res['LinodeID']
                 # Update linode Label to match name
-                api.linode_update(LinodeId=linode_id, Label='%s_%s' % (linode_id, name))
+                api.linode_update(LinodeId=linode_id, Label='%s-%s' % (linode_id, name))
                 # Update Linode with Ansible configuration options
                 api.linode_update(LinodeId=linode_id, LPM_DISPLAYGROUP=displaygroup, WATCHDOG=watchdog, **kwargs)
                 # Save server