added note about registered variables

docsite/rst/playbooks_variables.rst

@@ -558,6 +558,8 @@ While it's mentioned elsewhere in that document too, here's a quick syntax examp
 Registered variables are valid on the host the remainder of the playbook run, which is the same as the lifetime of "facts"
 in Ansible.  Effectively registered variables are just like facts.
 
+.. note:: If a task fails or is skipped, the variable still is registered with a failure or skipped status, the only way to avoid registering a variable is using tags.
+
 .. _accessing_complex_variable_data:
 
 Accessing Complex Variable Data