help center: Add a detail to /help/mute-a-stream.
help center: Add a detail to /help/mute-a-stream.

Indicate that muted streams are sorted to the bottom of their section.

zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip,zulip/zulip