More documentation tweaks (#2001)

* Change the title of some widget references to their class names

The widget reference index had a slight mixture of widget title styles, some
being their class name, others being "written English" type titles. This
settles on the titles always being the class name.

* Add a link to the ContentSwitcher to the widget gallery

No screenshot for this, on purpose. By definition this widget isn't visible,
except via other widgets that it's enclosing and handling.

* Have mkdocs watch the main nav file

* Mark the content switcher off the roadmap

docs/roadmap.md

@@ -41,7 +41,7 @@ Widgets are key to making user-friendly interfaces. The builtin widgets should c
     * [x] Error / warning variants
 - [ ] Color picker
 - [X] Checkbox
-- [ ] Content switcher
+- [X] Content switcher
 - [x] DataTable
     * [x] Cell select
     * [x] Row / Column select

docs/widget_gallery.md

@@ -35,6 +35,14 @@ A classic checkbox control.
 ```
 
 
+## ContentSwitcher
+
+A widget for containing and switching display between multiple child
+widgets.
+
+[ContentSwitcher reference](./widgets/content_switcher.md){ .md-button .md-button--primary }
+
+
 ## DataTable
 
 A powerful data table, with configurable cursors.

mkdocs-common.yml

@@ -80,6 +80,7 @@ plugins:
             - "!^can_replace$"
     watch:
       - mkdocs-common.yml
+      - mkdocs-nav.yml
       - mkdocs-offline.yml
       - mkdocs-online.yml
       - src/textual