Add reference to the DrRacket interface essentials from the Quick Start guide.

This adds a tag to DrRacket File menu docs.  It adds two margin notes
to the quick start, one linking to the essentials for using DrRacket,
and the other for saving Definitions.

Addresses PR 9501.

collects/scribblings/drracket/menus.scrbl

@@ -10,7 +10,7 @@
 
 @title{Menus}
 
-@section{@onscreen{File}}
+@section[#:tag "menu:file"]{@onscreen{File}}
 
 @itemize[
   

collects/scribblings/quick/quick.scrbl

@@ -44,6 +44,9 @@ start DrRacket.
 @; ----------------------------------------------------------------------
 @section{Set...}
 
+@margin-note{See @secref[#:doc '(lib "scribblings/drracket/drracket.scrbl") 
+                               "interface-essentials"] for a brief overview of
+                               the DrRacket IDE.}
 To draw pictures, we must first load some picture functions, which are
 part of a library for creating slide presentations.  Copy the
 following into the @defterm{definitions area}, which is the top text
@@ -406,7 +409,10 @@ Modules are named and distributed in various ways:
        @filepath{random.plt} library by @filepath{schematics} and then
        imports the @filepath{random.rkt} module.}
 
- @item{Some modules live relative to other modules, without
+ @item{@margin-note{To save your definitions, use @onscreen{Save Definitions} in DrRacket's
+                    @secref[#:doc '(lib "scribblings/drracket/drracket.scrbl") "menu:file"]
+                    menu.}
+       Some modules live relative to other modules, without
        necessarily belonging to any particular collection or package.
        For example, in DrRacket, if you save your definitions so far in a
        file @filepath{quick.rkt} and add the line