Add notice about call pattern to gd_v_wallman

src/gd_v_wallman.erl

@@ -1,3 +1,17 @@
+%%% @doc
+%%% The GajuDesk Wallet Manager
+%%%
+%%% This is an interface for managing multiple wallets.
+%%% A wallet is defined as a collection of accounts/keys.
+%%%
+%%% NOTE:
+%%%     Any call to `gd_con:show_ui(gd_v_wallman)' must be followed by a call to
+%%%     either `gd_v_wallman:to_front()' or `gd_v_wallman:first_run()' or else
+%%%     this UI process will just sit in the background (invisible) until told to
+%%%     do something.
+%%% @end
+
+
 -module(gd_v_wallman).
 -vsn("0.7.0").
 -author("Craig Everett <zxq9@zxq9.com>").