Doc: NR - 2.10.2 - Arabic Music - improved example

Doc: NR - 2.10.2 - Arabic Music - improved example

Issue 4778
Replace example in snippet with
that given by Bernhard Blöchl.

Minor line-spacing improvements.

[dak, 2020-01-29 22:47:55]

https://codereview.appspot.com/572600048/diff/548660043/Documentation/snippet...
File Documentation/snippets/new/non-traditional-key-signatures.ly (right):

https://codereview.appspot.com/572600048/diff/548660043/Documentation/snippet...
Documentation/snippets/new/non-traditional-key-signatures.ly:5:
version-specific, non-traditional, world-music"
Breaking this line breaks makelsr.py .  How did this get through?

I see that it was silently fixed in

commit c511518a4e7669ac7263f8a28565debefe25a358
Author: James Lowe <pkx166h@runbox.com>
Date:   Mon Apr 15 21:03:57 2019 +0100

    makelsr run for previous commit
    
    Changes made based on commit
    Doc: NR - 2.10.2 - Arabic Music - improved example
    03f78e3e7bda039ea08744d3736bfa4a39dea2a4

diff --git a/Documentation/snippets/new/non-traditional-key-signatures.ly
b/Documentation/snippets/new/non-traditional-key-signatures.ly
index f5967009bd..f2a16ca841 100644
--- a/Documentation/snippets/new/non-traditional-key-signatures.ly
+++ b/Documentation/snippets/new/non-traditional-key-signatures.ly
@@ -1,8 +1,7 @@
 \version "2.19.21"
 
 \header {
-  lsrtags = "contemporary-notation, pitches, staff-notation,
-  version-specific, non-traditional, world-music"
+  lsrtags = "contemporary-notation, pitches, staff-notation, version-specific,
non-traditional, world-music"

which is a really, really, really bad idea since obviously makelsr runs are not
cherry-picked, so this fix should have been made in a separate commit.  Took me
a few hours (after all, make doc will take about half an hour on my computer). 
Please folks, don't pack corrective commits into the commits running scripts.