doc: add FAQ about iTerm2 and broken colors

Closes #2.

doc/startify.txt

@@ -164,6 +164,15 @@ options like this:
 It's because Vim loads the list from viminfo only once, at startup.
 
 
+"I use OSX and iTerm2 and have broken colors!"
+----------------------------------------------
+
+Nothing this plugin could do about. Try playing round with 'sessionoptions'.
+Some people swear it works for them with these settings:
+
+    set sessionoptions=blank,curdir,folds,help,tabpages,winpos
+
+
 ==============================================================================
 6. About the author                                            *startify-author*