Clean-up demo scripts & documentation (#12143)

* Rewrites the demo documentation to be clearer, accurate, and moves it to our documentation tree.
* Improvements to the demo scripts:
	* `clean.sh` now runs `stop.sh` first to avoid zombie processes.
	* Uses more modern Synapse configuration (and removes some obsolete configuration).
	* Consistently use the HTTP ports for server name, etc.
	* Remove the `demo/etc` directory and place everything into the `demo/808x` directories.

3 files changed, 44 insertions, 1 deletions

diff --git a/docs/SUMMARY.md b/docs/SUMMARY.md
index ef9cabf555..21f80efc99 100644
--- a/docs/SUMMARY.md
+++ b/docs/SUMMARY.md
@@ -82,6 +82,7 @@
   - [Release Cycle](development/releases.md)
   - [Git Usage](development/git.md)
   - [Testing]()
+    - [Demo scripts](development/demo.md)
   - [OpenTracing](opentracing.md)
   - [Database Schemas](development/database_schema.md)
   - [Experimental features](development/experimental_features.md)
diff --git a/docs/development/demo.md b/docs/development/demo.md
new file mode 100644
index 0000000000..4277252ceb
--- /dev/null
+++ b/docs/development/demo.md
@@ -0,0 +1,41 @@
+# Synapse demo setup
+
+**DO NOT USE THESE DEMO SERVERS IN PRODUCTION**
+
+Requires you to have a [Synapse development environment setup](https://matrix-org.github.io/synapse/develop/development/contributing_guide.html#4-install-the-dependencies).
+
+The demo setup allows running three federation Synapse servers, with server
+names `localhost:8080`, `localhost:8081`, and `localhost:8082`.
+
+You can access them via any Matrix client over HTTP at `localhost:8080`,
+`localhost:8081`, and `localhost:8082` or over HTTPS at `localhost:8480`,
+`localhost:8481`, and `localhost:8482`.
+
+To enable the servers to communicate, self-signed SSL certificates are generated
+and the servers are configured in a highly insecure way, including:
+
+* Not checking certificates over federation.
+* Not verifying keys.
+
+The servers are configured to store their data under `demo/8080`, `demo/8081`, and
+`demo/8082`. This includes configuration, logs, SQLite databases, and media.
+
+Note that when joining a public room on a different HS via "#foo:bar.net", then
+you are (in the current impl) joining a room with room_id "foo". This means that
+it won't work if your HS already has a room with that name.
+
+## Using the demo scripts
+
+There's three main scripts with straightforward purposes:
+
+* `start.sh` will start the Synapse servers, generating any missing configuration.
+  * This accepts a single parameter `--no-rate-limit` to "disable" rate limits
+    (they actually still exist, but are very high).
+* `stop.sh` will stop the Synapse servers.
+* `clean.sh` will delete the configuration, databases, log files, etc.
+
+To start a completely new set of servers, run:
+
+```sh
+./demo/stop.sh; ./demo/clean.sh && ./demo/start.sh
+```
diff --git a/docs/federate.md b/docs/federate.md
index 5107f995be..df4c87da51 100644
--- a/docs/federate.md
+++ b/docs/federate.md
@@ -63,4 +63,5 @@ release of Synapse.
 
 If you want to get up and running quickly with a trio of homeservers in a
 private federation, there is a script in the `demo` directory. This is mainly
-useful just for development purposes. See [demo/README](https://github.com/matrix-org/synapse/tree/develop/demo/).
+useful just for development purposes. See
+[demo scripts](https://matrix-org.github.io/synapse/develop/development/demo.html).