Web: Download: Add introductory text (issue 40510046)

[lilyliska]

Reviewers: ,

Description:
Web: Download: Add introductory text

This addresses the initial issue discussed on lilypond-user:
too many people don't understand what they download and get
stuck on not being able to "open the LilyPond program".

Add a text that explains the compiled approach and makes clear
one should have LilyPond _and_ an editing environment.

The current warning (which apparently wasn't sufficient)
has been removed from this page but is kept on the subpages
in case someone reaches them by a direct link.

Please review this at https://codereview.appspot.com/40510046/

Affected files (+31, -2 lines):
  M Documentation/web/download.itexi


Index: Documentation/web/download.itexi
diff --git a/Documentation/web/download.itexi  
b/Documentation/web/download.itexi
index  
91bd1a334ca98a8b106c7cffdbe0dbcd1d7c0d92..46eebd9f850867872f0e7ef06b3a21d68d3d5cd1  
100644
--- a/Documentation/web/download.itexi
+++ b/Documentation/web/download.itexi
@@ -32,12 +32,41 @@ our @ref{Text input}.}
   @heading Downloads for LilyPond @versionStable
 @end ifset

address@hidden
-
 @divEnd

 @divClass{link-headings}

address@hidden
address@hidden Before you proceed ...
+
+... you should be aware of some facts and concepts.
+
+LilyPond is a @strong{command line application} translating files written  
in
+LilyPond's music description language into graphical
+scores.  It does @strong{not} constitute a working environment.  What you  
will be
+working with for entering your scores is either a @emph{text editor} of  
your
+choice, or a dedicated editing tool for LilyPond files.
+
+If you want you can go to @ref{Text input} and learn more about LilyPond's
+input language concept.
+
address@hidden I'm new to LilyPond and don't have a dedicated editor yet
+
+If you don't already have an editing environment for LilyPond you should
+go to @ref{Editing} now. Apart from getting information on the editing
+concept you'll find a list of known editors. For beginners it is
+recommended to download and install either @strong{Frescobaldi} or
address@hidden Both can take care of installing LilyPond for you.
+
address@hidden I'm already a LilyPond user and just want a new version
+
+However, if you already have and editing environment and simply want
+to install a new LilyPond version you can proceed below.
+
+
address@hidden
+
+
 @divClass{column-left-top}
 @subheading For users