meta: notify #t-rustdoc Zulip stream on backport nominations

triagebot.toml

@@ -389,13 +389,47 @@ message_on_reopen = "Issue #{number} has been reopened."
 
 [notify-zulip."T-rustdoc"]
 required_labels = ["I-nominated"]
-zulip_stream = 266220 # #rustdoc
+zulip_stream = 266220 # #t-rustdoc
 topic = "nominated: #{number}"
 message_on_add = """\
 @*T-rustdoc* issue #{number} "{title}" has been nominated for `T-rustdoc` discussion.
 """
 message_on_remove = "Issue #{number}'s nomination request has been removed."
 
+# FIXME(fmease): Consider adding support for `stable-nominated`, too.
+# FIXME(fmease): This is not ideal, we're essentially preventing other teams from
+#                adding their own custom logic for `beta-nominated`.
+#                We could swap `beta-nominated` and `T-rustdoc` just like above ("T-rustdoc", "I-nominated").
+#                https://github.com/rust-lang/rust/pull/82689#discussion_r585159710
+#                However, that's far from ideal as the removal of "beta-nominated" wouldn't be detected
+#                IIUC.
+# FIXME(fmease): Ideally, we would also send a message or resolve the Zulip topic once `beta-accepted`
+#                has been added.
+[notify-zulip."beta-nominated"]
+required_labels = ["T-rustdoc"]
+zulip_stream = 266220 # #t-rustdoc
+topic = "beta-nominated: #{number}"
+# FIXME(fmease): Unfortunately, Zulip polls may not contain any other text
+#                https://zulip.com/help/create-a-poll#troubleshooting
+message_on_add = """\
+@*T-rustdoc* PR #{number} "{title}" has been nominated for beta backport.
+"""
+# FIXME(fmease): ... consider patching `triagebot` to allow posting several messages.
+# message_on_add = [
+#     """\
+# @*T-rustdoc* PR #{number} "{title}" has been nominated for beta backport.
+# """,
+#     """\
+# /poll Approve beta backport of #{number}?
+# approve
+# decline
+# don't know
+# """,
+# ]
+message_on_remove = "PR #{number}'s beta-nomination has been removed."
+message_on_close = "PR #{number} has been closed. Thanks for participating!"
+message_on_reopen = "PR #{number} has been reopened. Pinging @*T-rustdoc*."
+
 [notify-zulip."I-types-nominated"]
 zulip_stream = 326866 # #T-types/nominated
 topic = "#{number}: {title}"