Fix Bash example

Author: ehmicky

examples/convert.sh

@@ -4,8 +4,9 @@
 #   - first install `unix-permissions`
 #   - then `bash node_modules/unix-permissions/examples/convert.sh`
 
-# The following `alias` is only needed for this example.
+# The following lines are only needed for this example.
 # In a terminal, you should directly use `unix-permissions` instead.
+shopt -s expand_aliases
 alias unix-permissions='./build/src/bin/index.js'
 
 unix-permissions convert.symbolic 111 # a=x