Fixes the URLRedirects for "help/about-streams-and-topics" and
"help/streams-and-topics" to go to "/help/introduction-to-topics"
since "help/channels-and-topics" has been redirected to that URL.
Updates all the https://chat.zulip.org/#narrow/stream/ links in the
docs and comments to use the new /channel/ path. All these links are
for documentation/reference purposes only and thus, can be bulk-updated.
This commit is a part of the effort to rename stream to channel.
Updates descriptive text that refer to Zulip channels in the
`docs/contributing` files to use channel instead of stream.
Part of the stream to channel rename project.
Lauryn Menard
Sayam Samal
Karl Stolley
Alya Abbott