Adds API changelog feature level 1 and associated Changes notes
for when the `stream_id` parameter in the `PATCH /messages/message_id`
was added, and for when the `prev_stream` field was added to edit
history information for messages.
We're adding these to the Zulip 3.0 feature level 1 because
commit 843345dfee that introduced this field and this parameter
to the server / backend code was merged before the commit that added
the API feature level tracking, commit e3b90a5ec8, at level 1.
2f196bff19