Gedit/gtksourceview language spec: add 'in' keyword

Author: SimonSapin

src/etc/gedit/share/gtksourceview-3.0/language-specs/rust.lang

@@ -50,6 +50,7 @@
 		<keyword>for</keyword>
 		<keyword>if</keyword>
 		<keyword>impl</keyword>
+		<keyword>in</keyword>
 		<keyword>let</keyword>
 		<keyword>log</keyword>
 		<keyword>loop</keyword>