Document the 'ui' word

TODO.txt

@@ -7,6 +7,17 @@
 
 + 0.88:
 
+- poorly documented vocabs:
+  - alien
+  - assembler
+  - cocoa
+  - command-line
+  - compiler
+  - completion
+  - image
+  - interpreter
+  - objc
+  - optimizer
 - calling 'see' with an nonexistent method should be an error
 - grid-lines are rendered incorrectly
 - interactor: show stack effect for word at caret in status bar

core/ui/ui.facts

@@ -0,0 +1,5 @@
+IN: gadgets
+
+HELP: ui
+{ $description "Starts the Factor UI." }
+{ $see-also tty } ;