Update readme

README.md

@@ -6,8 +6,32 @@ Testbed for full mesh video chat.
 
 You must first run a local Synapse server on port 8080
 
+Then install the dependencies:
+
 ```
 cd matrix-video-chat
 npm install
+```
+
+Locally checkout the [robertlong/full-mesh-voip](https://github.com/matrix-org/matrix-js-sdk/tree/robertlong/full-mesh-voip) branch of the matrix-js-sdk.
+
+```
+cd matrix-js-sdk
+git checkout robertlong/full-mesh-voip
+yarn
+yarn build
+npm link
+```
+
+Link the matrix-js-sdk into the matrix-video-chat project:
+
+```
+cd matrix-video-chat
+npm link matrix-js-sdk
+```
+
+Finally run the development server
+
+```
 npm run dev
 ```