Move command docs and script to contrib/docs

contrib/docs/commands/unicode.md

@@ -0,0 +1,12 @@
+### unicode
+Toggle unicode input enabled/disabled in interactive shell
+
+Usage: `unicode`
+<pre>
+Unicode mode is experimental, you might experience
+ some issues interacting with the console
+ (e.g. history navigation fails).
+
+Type "help --unicode" for further info
+Note: this command is only available on some versions of Windows
+</pre>