Update tags, make CLI reference page

docs/_data/sidebars/pmd_sidebar.yml

@@ -31,12 +31,12 @@ entries:
   - title: User Documentation
     output: web, pdf
     folderitems:
-    - title: Getting started
-      url: /pmd_userdocs_getting_started.html
-      output: web, pdf
     - title: Installation and basic CLI usage
       url: /pmd_userdocs_installation.html
       output: web, pdf
+    - title: Full CLI reference
+      url: /pmd_userdocs_cli_reference.html
+      output: web, pdf
     - title: Understanding rulesets
       url: /pmd_userdocs_understanding_rulesets.html
       output: web, pdf

docs/_data/tags.yml

@@ -1,15 +1,10 @@
 allowed-tags:
-  - getting_started
+  - essentials      # Essential references for any user
+  - rule_references # For the rule indices
   - release_notes
-  - content_types
-  - navigation
-  - formatting
-  - publishing
-  - single_sourcing
-  - special_layouts
-  - collaboration
   - news
   - troubleshooting
-  - mobile
-  - customizing
+  - customizing     # For pages about configuration
+  - userdocs        # Pages about usage, making rulesets, configuring rules,
+  - extending       # Pages about writing rules, metrics, properties, etc
   - languages