Clarify Subscription page language

Summary: This says "Edit Subscription" but the page only lets you update the payment method for autopay. I think this is confusing users. I tried to find the best language here, but suggest something else if you prefer.

Test Plan: Review language on sample subscription page.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12451

Differential Revision: https://secure.phabricator.com/D17944

src/applications/phortune/controller/subscription/PhortuneSubscriptionViewController.php

@@ -43,8 +43,8 @@ final class PhortuneSubscriptionViewController extends PhortuneController {
 
     $curtain->addAction(
       id(new PhabricatorActionView())
-        ->setIcon('fa-pencil')
+        ->setIcon('fa-credit-card')
-        ->setName(pht('Edit Subscription'))
+        ->setName(pht('Manage Autopay'))
         ->setHref($edit_uri)
         ->setDisabled(!$can_edit)
         ->setWorkflow(!$can_edit));