docs: Change chat.zulip.org links to zulip.com/developer-community.

This helps increase the probability that folks read the guidelines for how the
chat.zulip.org community works and what streams to use before arriving there.

Fixes #19827.

docs/contributing/code-style.md

@@ -28,7 +28,8 @@ Look at the surrounding code, or a similar part of the project, and try
 to do the same thing. If you think the other code has actively bad
 style, fix it (in a separate commit).
 
-When in doubt, ask in [chat.zulip.org](https://chat.zulip.org).
+When in doubt, ask in
+[#development help](https://chat.zulip.org/#narrow/stream/49-development-help).
 
 ## Lint tools
 

docs/contributing/gsoc-ideas.md

@@ -80,8 +80,8 @@ tasks that are great for first-time contributors. Use
 [our first-time Zulip developer guide](../overview/contributing.html#your-first-codebase-contribution)
 to get your Zulip development environment set up and to find your first issue. If you have any
 trouble, please speak up in
-[#GSoC](https://chat.zulip.org/#narrow/stream/14-GSoC) on
-[the Zulip development community server](https://zulip.com/developer-community/)
+[#GSoC](https://chat.zulip.org/#narrow/stream/14-GSoC) in
+[the Zulip development community server][development-community]
 (use your name as the topic).
 
 ## Application tips, and how to be a strong candidate
@@ -126,8 +126,8 @@ application deadline.
 
 We are more interested in candidates if we see them submitting good
 contributions to Zulip projects, helping other applicants on GitHub
-and on
-[chat.zulip.org](https://zulip.com/developer-community/),
+and in
+[the Zulip development community][development-community],
 learning from our suggestions,
 [trying to solve their own obstacles and then asking well-formed
 questions](https://blogs.akamai.com/2013/10/you-must-try-and-then-you-must-ask.html),
@@ -170,14 +170,16 @@ projects. We usually decide who will mentor which projects based in
 part on who is a good fit for the needs of each student as well as
 technical expertise as well as who has available time during the
 summer. You can reach us via
-[#GSoC](https://chat.zulip.org/#narrow/stream/14-GSoC) on [the Zulip
-development community server](https://zulip.com/developer-community/),
+[#GSoC](https://chat.zulip.org/#narrow/stream/14-GSoC) in
+[the Zulip development community server][development-community],
 (compose a new stream message with your name as the topic).
 
 Zulip operates under group mentorship. That means you should
-generally post in public streams on chat.zulip.org, not send private
+generally post in public streams in
+[the Zulip development community][development-community], not send private
 messages, for assistance. Our preferred approach is to just post in
-an appropriate public stream on chat.zulip.org and someone will help
+an appropriate public stream in
+[the Zulip development community][development-community] and someone will help
 you. We list the Zulip contributors who are experts for various
 projects by name below; they will likely be able to provide you with
 the best feedback on your proposal (feel free to @-mention them in
@@ -196,11 +198,12 @@ few contributions! Everyone makes mistakes getting started. Just
 make sure you don't make the same mistakes next time).
 
 Once you have several PRs merged (or at least one significant PR
-merged), you can start discussing with the Zulip development community
+merged), you can start discussing with
+[the Zulip development community][development-community]
 the project you'd like to do, and developing a specific project plan.
-We recommend discussing what you're thinking in public streams on
-chat.zulip.org, so it's easy to get quick feedback from whoever is
-online.
+We recommend discussing what you're thinking in public streams in
+[the Zulip development community][development-community],
+so it's easy to get quick feedback from whoever is online.
 
 ## Project ideas
 
@@ -588,7 +591,9 @@ Where should you publish your draft? We prefer Dropbox Paper or
 Google Docs, since those platforms allow people to look at the text
 without having to log in or download a particular app, and you can
 update the draft as you improve your idea. In either case, you should
-post the draft for feedback in chat.zulip.org.
+post the draft for feedback in [the Zulip development community][development-community].
+
+[development-community]: https://zulip.com/developer-community/
 
 Rough is fine! The ideal first draft to get feedback from the
 community on should include primarily (1) links to your contributions

docs/contributing/summer-with-zulip.md

@@ -34,8 +34,10 @@ materials](https://developers.google.com/open-source/gsoc/resources/manual).
 - Mentors and students should stay in close contact, both with each other and
   the rest of the Zulip community. We recommend the following:
 
-  - Daily checkins on #checkins on chat.zulip.org; ideally at some time of day
-    you can both be online, but when not possible, async is better than nothing!
+  - Daily checkins on #checkins in
+    [the Zulip development community](https://zulip.com/developer-community/); ideally
+    at some time of day you can both be online, but when not
+    possible, async is better than nothing!
 
     - We prefer checkins in public streams, since it makes easier for
       other contributors to keep track of what everyone else is
@@ -54,9 +56,9 @@ materials](https://developers.google.com/open-source/gsoc/resources/manual).
     need help learning, and time-saving tricks.
 
   - If you need feedback from the community / decisions made, ask in the
-    appropriate public stream on [chat.zulip.org](https://chat.zulip.org). Often
-    someone can provide important context that you need to succeed in your
-    project.
+    appropriate public stream in
+    [the Zulip development community](https://zulip.com/developer-community/). Often
+    someone can provide important context that you need to succeed in your project.
 
   - Communicate clearly, especially in public places! You'll get much more
     useful feedback to a well-written Zulip message or GitHub issue comment than