Feedback when updating RSS feed details

[opk12]

After that I change details for an RSS feed and click Save, feedback should appear near the button.

• When I click: Saving... This helps on a flaky connection (see below), clears out previous feedback (to avoid ambiguity in case I edit/save twice), shows that the web page is not hung or something.
• On success: Saved. My WiFi is flaky downstairs, so I don't know if I can already close the tab, or it's waiting for the server response.
• On failure: Not saved, error. Today, the error appears above Feeds subscribed to. This is far above than Save, so it is not visible.