update readme

Author: DannyBen

README.md

@@ -238,6 +238,7 @@ short form).
 `arg`      | If the flag requires an argument, specify its name here.
 `required` | Specify if this flag is required.
 `default`  | The value to use in case it is not provided by the user. Implies that this flag is optional, and only makes sense when the flag has an argument.
+`allowed`  | For flags with an argument, you can limit the allowed values by providing an array.
 
 #### Special handling for -v and -h
 

lib/bashly/views/flag/case.erb

@@ -8,7 +8,7 @@
     <%- if allowed -%>
     allowed="<%= allowed.join '|' %>"
     if [[ ! ${args[<%= name %>]} =~ $allowed ]]; then
-      printf "%s\n" "<%= strings[:disallowed_flag] % { name: name, allowed: allowed.join(', ') } %>\n"
+      printf "%s\n" "<%= strings[:disallowed_flag] % { name: name, allowed: allowed.join(', ') } %>"
       exit 1
     fi
     <%- end -%>