Description: Add gem extension

--- misc/mc.ext.in
+++ misc/mc.ext.in
@@ -107,7 +107,7 @@
 ### Archives ###
 
 # .tgz, .tpz, .tar.gz, .tar.z, .tar.Z, .ipk
-regex/\.t([gp]?z|ar\.g?[zZ])$|\.ipk$
+regex/\.t([gp]?z|ar\.g?[zZ])$|\.ipk|\.gem$
 	Open=%cd %p#utar
 	View=%view{ascii} gzip -dc %f 2>/dev/null | tar tvvf -