Reverts parts of my last PR (#177)

Cannot mount data directory at the moment, we need to make code-server
override all binaries in there instead of reusing and will wait
until the new Dockerfile is pushed before removing the default
entrypoint from README.md

Author: nhooyr

README.md

@@ -9,7 +9,7 @@
 
 Try it out:
 ```bash
-docker run -p 127.0.0.1:8443:8443 -v "${PWD}:/root/project" -v ~/.code-server:/root/.code-server codercom/code-server --allow-http --no-auth
+docker run -p 127.0.0.1:8443:8443 -v "${PWD}:/root/project" codercom/code-server code-server --allow-http --no-auth
 ```
 
 - Code on your Chromebook, tablet, and laptop with a consistent dev environment.