Fix Docker example errors and make it POSIX compliant (#22635)

content/actions/creating-actions/dockerfile-support-for-github-actions.md

@@ -85,9 +85,8 @@ Using the example Dockerfile above, {% data variables.product.product_name %} wi
 
 # `$#` expands to the number of arguments and `$@` expands to the supplied `args`
 printf '%d args:' "$#"
-printf $' \'%s\'' "$@"
-printf ' <%s>' "$@"
-echo
+printf " '%s'" "$@"
+printf '\n'
 ```
 
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