[iOS] Added subtitle for the feed management page following entrypoint.

Added a new subtitle to the following feed management page entrypoint.

Bug: b/284006584
Change-Id: I1472d950897899e4689d7ffa84ca4e78eeea5a68
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4582480


Commit-Queue: Adam Arcaro <adamta@google.com>
Commit-Queue: Guillem Perez <guiperez@google.com>
Auto-Submit: Guillem Perez <guiperez@google.com>
Reviewed-by: Adam Arcaro <adamta@google.com>
Cr-Commit-Position: refs/heads/main@{#1152626}