add features section

Signed-off-by: cinereal <cinereal@riseup.net>

architecture-docs/architecture.md

@@ -107,6 +107,16 @@ Considered alternatives include:
 
 - file storage: less centralised for backups
 
+## Features
+
+Primary platform features toward operators will include:
+
+1. install selected applications
+1. configure applications
+1. update applications
+1. switch to a different host (service portability)
+1. user management
+
 ## Architecture
 
 At the core of Fediversity lies a NixOS configuration module for a set of selected applications.