Fix copy.

app/views/projects/_issuable_form.html.haml

@@ -18,7 +18,7 @@
           This merge request is marked a <strong>Work In Progress</strong>.
           When it's ready, remove the <code>WIP</code> prefix from the title to allow it to be accepted.
         - else
-          To prevent this merge request from being accepted until it's ready, 
+          To prevent this merge request from being accepted before it's ready, 
           mark it a <strong>Work In Progress</strong> by starting the title with <code>[WIP]</code> or <code>WIP:</code>.
 .form-group.issuable-description
   = f.label :description, 'Description', class: 'control-label'