"Post" is too terse

I think we can go back to the longer label now that the hotkeys aren't
inside the button

app/views/cards/comments/_new.html.erb

@@ -17,7 +17,7 @@
         <span class="flex-inline align-center gap">
           <%= form.button class: "comment__submit btn btn--reversed",
               data: { form_target: "submit" }, disabled: true do %>
-            <span>Post</span>
+            <span>Post this comment</span>
           <% end %>
           <span class="hide-on-touch txt-subtle">
             <kbd class="txt-x-small"><%= hotkey_label([ "ctrl", "enter" ]) %></kbd>