Staged docs releases (#50136)

Closes #ISSUE

Before you mark this PR as ready for review, make sure that you have:
- [x] Added a solid test coverage and/or screenshots from doing manual
testing
- [x] Done a self-review taking into account security and performance
aspects
- [x] Aligned any UI changes with the [UI
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)

Release Notes:

- N/A *or* Added/Fixed/Improved ...

.cloudflare/docs-proxy/src/worker.js

@@ -1,7 +1,22 @@
 export default {
   async fetch(request, _env, _ctx) {
     const url = new URL(request.url);
-    url.hostname = "docs-anw.pages.dev";
+
+    if (url.pathname === "/docs/nightly") {
+      url.hostname = "docs-nightly.pages.dev";
+      url.pathname = "/docs/";
+    } else if (url.pathname.startsWith("/docs/nightly/")) {
+      url.hostname = "docs-nightly.pages.dev";
+      url.pathname = url.pathname.replace("/docs/nightly/", "/docs/");
+    } else if (url.pathname === "/docs/preview") {
+      url.hostname = "docs-preview-5xd.pages.dev";
+      url.pathname = "/docs/";
+    } else if (url.pathname.startsWith("/docs/preview/")) {
+      url.hostname = "docs-preview-5xd.pages.dev";
+      url.pathname = url.pathname.replace("/docs/preview/", "/docs/");
+    } else {
+      url.hostname = "docs-anw.pages.dev";
+    }
 
     let res = await fetch(url, request);