Changed reference trigger from << to xref.

src/docs/asciidoc/wiki/atom_editor.adoc

@@ -110,11 +110,11 @@ The Atom AsciiDoc packages add great functionality to the editor, but they do no
 ----
 '.source.asciidoc':
   'Inter-Doc Cross Reference':
-    'prefix': '<<'
+    'prefix': 'xref'
     'body': '<<${1:path/to/wiki/page}#,${2:custom label text}>>'
 ----
 
-Thereafter just type kbd:[<<]  and hit kbd:[Tab] to insert an Inter-Document Cross Reference link. You can then use the kbd:[Tab] key to cycle through each tab stop when your ready.
+Thereafter just type kbd:[xref] and hit kbd:[Tab] to insert an Inter-Document Cross Reference link. You can then use the kbd:[Tab] key to cycle through each tab stop when your ready.
 
 You can help the jMonkey community by adding new snippets. Use your editor and edit the <<wiki/atom_snippets#,Atom Snippets>> document. Make sure to announce any proposed changes on the link:https://hub.jmonkeyengine.org/[jMonkeyEngine Forum] under the topic "`Documentation`" first so others are aware and can test out your proposed change.
 

src/docs/asciidoc/wiki/atom_snippets.adoc

@@ -35,6 +35,6 @@ Edit this file to add snippets to the snippets.cson file for the link:https://at
 # http://flight-manual.atom.io/using-atom/sections/basic-customization/#_cson
 '.source.asciidoc':
   'Inter-Doc Cross Reference':
-    'prefix': '<<'
+    'prefix': 'xref'
     'body': '<<${1:path/to/wiki/page}#,${2:custom label text}>>'
 ----