namespace facts (#18445)

* namespace facts

always namespace facts, make the polluting of 'main' conditional on config

* updated to 2.4

* Update intro_configuration.rst

examples/ansible.cfg

@@ -288,6 +288,10 @@
 # only update this setting if you know how this works, otherwise it can break module execution
 #network_group_modules=['eos', 'nxos', 'ios', 'iosxr', 'junos', 'vyos']
 
+# This keeps facts from polluting the main namespace as variables.
+# Setting to True keeps them under the ansible_facts namespace, the default is False
+#restrict_facts_namespace: True
+
 [privilege_escalation]
 #become=True
 #become_method=sudo