updated plugin docs (#30490)

* updated  docs

- for devs:
  - added inventory/vars section
  - made some updates to general section and other plugin types
- for users:
 - added 'user' plugin section to start describing the plugins
 - docs on types, what they are and how to use

- removed ref to deleted AUTHORS file
- corrected several typos/headers
- added descriptions to config.rst template
- ignore generated files for cli/plugins and config
- remove new generated files on `make clean`
- moved details from devguid and intro doc to plugin specific pages
- pretied up lookup notes
- changed precedence ref to not conflict config
- removed duplicate config data, as config is autogenerated and up to date
- put new plugins under playbooks
- added `pass` cause rst/python dislikes fractions
- removed dupe in .gitignore, alpha sorted to avoid moar dupes
- added try cause rst/python freaks out

* generate plugins into their own dir

only do plugins that support docs
use toctree from main plugins page

lib/ansible/plugins/inventory/constructed.py

@@ -13,17 +13,22 @@ DOCUMENTATION = '''
         - Uses a YAML configuration file to define var expresisions and group conditionals
         - The Jinja2 conditionals that qualify a host for membership.
         - The JInja2 exprpessions are calculated and assigned to the variables
-        - Only variables already available from previous inventories can be used for templating.
-        - Failed expressions will be ignored (assumes vars were missing).
+        - Only variables already available from previous inventories or the fact cache can be used for templating.
+        - When `strict` is False, failed expressions will be ignored (assumes vars were missing).
     extends_documentation_fragment:
       - constructed
 '''
 
 EXAMPLES = '''
     # inventory.config file in YAML format
-    plugin: comstructed
+    plugin: constructed
+    strict: False
     compose:
         var_sum: var1 + var2
+
+        # this variable will only be set if I have a persistent fact cache enabled (and have non expired facts)
+        # `strict: False` will skip this instead of producing an error if it is missing facts.
+        server_type: "ansible_hostname | regex_replace ('(.{6})(.{2}).*', '\\2')"
     groups:
         # simple name matching
         webservers: inventory_hostname.startswith('web')