add self-hosting section

Author: fkwp

docs/README.md

@@ -5,3 +5,4 @@ This folder contains documentation for Element Call setup and usage.
 - [Embedded vs standalone mode](./embedded-standalone.md)
 - [Url format and parameters](./url-params.md)
 - [Global JS controls](./controls.md)
+- [Self-Hosting](./self-hosting.md)