Add bundle option to mdl

ale_linters/markdown/mdl.vim

@@ -10,9 +10,13 @@ endfunction
 
 function! ale_linters#markdown#mdl#GetCommand(buffer) abort
     let l:executable = ale_linters#markdown#mdl#GetExecutable(a:buffer)
+    let l:exec_args = l:executable =~? 'bundle$'
+    \   ? ' exec mdl'
+    \   : ''
+
     let l:options = ale#Var(a:buffer, 'markdown_mdl_options')
 
-    return ale#Escape(l:executable)
+    return ale#Escape(l:executable) . l:exec_args
     \   . (!empty(l:options) ? ' ' . l:options : '')
 endfunction