add basic structure for additional features documentation

Setting the raw frame with overview, short descriptions like in code
and already revealing skill levels.

Based on the current (recently modified) structure of the feature settings.

Detailed descriptions in work and coming with later commits as well as
a dedicated admin section for that topic. Better menu integration
may be possible with Andrew's new doco structure work in progress later.

1 files changed, 33 insertions, 0 deletions

diff --git a/doc/feature/additional/overview.md b/doc/feature/additional/overview.md
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+[chset]: /settings "Channel Settings"
+[ftset]: /settings/features "Additional Features Settings"
+[ftgen]: /help/feature/additional/general "General Features"
+[ftacc]: /help/feature/additional/access "Access Control and Permissions"
+[ftcom]: /help/feature/additional/composition "Post Composition Features"
+[ftfil]: /help/feature/additional/filtering "Network and Stream Filtering"
+[ftpos]: /help/feature/additional/posts "Post/Comment Tools"
+
+
+# Additional Features
+
+<!-- TODO: Introduction to additional features -->
+
+<!-- TODO: Short info and crosslink on techlevels -->
+
+You can switch the features on and off from the
+[Additional Features][ftset] link in the [Channel Settings][chset].
+
+<!-- TODO: Infos about feature visibility and causes/dependencies -->
+
+The following pages decribe all the available features
+grouped in the same way as they are with the accordion tabs on the
+[Additional Features][ftset] settings page:
+
+[General Features][ftgen]
+
+[Access Control and Permissions][ftacc]
+
+[Post Composition Features][ftcom]
+
+[Network and Stream Filtering][ftfil]
+
+[Post/Comment Tools][ftpos]