Set up mdbook in github pages (#26367)

docs/SUMMARY.md

@@ -0,0 +1,38 @@
+# Summary
+
+-   [Introduction](../README.md)
+
+# Usage
+
+-   [Betas](betas.md)
+-   [Labs](labs.md)
+
+# Setup
+
+-   [Config](config.md)
+-   [Custom home page](custom-home.md)
+-   [Kubernetes](kubernetes.md)
+-   [Jitsi](jitsi.md)
+-   [Encryption](e2ee.md)
+
+# Build
+
+-   [Customisations](customisations.md)
+-   [Modules](modules.md)
+-   [Native Node modules](native-node-modules.md)
+
+# Contribution
+
+-   [Choosing an issue](choosing-an-issue.md)
+-   [Translation](translating.md)
+-   [Netlify builds](pr-previews.md)
+-   [Code review](review.md)
+
+# Development
+
+-   [App load order](app-load.md)
+-   [Translation](translating-dev.md)
+-   [Theming](theming.md)
+-   [Memory profiling](memory-profiles-and-leaks.md)
+-   [Jitsi](jitsi-dev.md)
+-   [Feature flags](feature-flags.md)