implemented loop pausing (#17289)

* implemented loop pausing

- added loop pause to changelog
- only pause between iterations, avoid 1st/last
- added example to docs

* fixed note placement

* else

* added docs for loop_control: label

lib/ansible/playbook/loop_control.py

@@ -30,6 +30,7 @@ class LoopControl(Base):
 
     _loop_var = FieldAttribute(isa='str')
     _label    = FieldAttribute(isa='str')
+    _pause    = FieldAttribute(isa='int')
 
     def __init__(self):
         super(LoopControl, self).__init__()