Minor doc updates

README.adoc

@@ -147,8 +147,6 @@ To update:
 To get up and running with the smallest footprint on your system, you may use the Polkadot Docker image.
 You can either build it yourself (it takes a while...):
 
-NOTE: Make sure you build from the project root, *not* from the `./docker` folder.
-
 [source, shell]
 ----
 ./docker/build.sh
@@ -160,7 +158,7 @@ If you run into issues with polkadot when using docker, please run the following
 (replace the tag with the appropriate one if you do not use latest):
 
 [source, shell]
-docker run --rm -it chevdor/polkadot:latest version
+docker run --rm -it chevdor/polkadot:latest polkadot --version
 
 This will show you the polkadot version as well as the git commit ref that was used to build your container.
 Just paste that in the issue you create.

docker/readme-docker.adoc

@@ -5,7 +5,7 @@
 
 Run the following command
 
-	docker run -d chevdor/polkadot:latest polkadot
+	docker run -d -P --name polkadot chevdor/polkadot:latest
 
 === Building the image