Add exclude example file

exclude

@@ -0,0 +1,18 @@
+/bin
+/boot
+/dev
+/media
+/mnt
+/proc
+/run
+/snap
+/sys
+/tmp
+/usr
+/var/tmp
+/var/snap
+/var/cache
+**/share/Steam
+/home/**/Downloads
+/home/**/Dropbox
+/home/wouter/isabella