Makefile: fix docker-shell command line

- Fix volume mounting (positional argument to `-v`)
- Correct the make target name in README

Updates tailscale/corp#19670

Signed-off-by: Anton Tolchanov <anton@tailscale.com>

Makefile

@@ -265,7 +265,7 @@ docker-all: docker-build-image docker-run-build $(DOCKER_IMAGE)
 .PHONY: docker-shell
 docker-shell: ## Builds a docker image with the android build env and opens a shell
 	docker build  -f docker/DockerFile.amd64-shell -t tailscale-android-shell-amd64 .
-	docker run -v --rm $(CURDIR):/build/tailscale-android -it tailscale-android-shell-amd64
+	docker run --rm -v $(CURDIR):/build/tailscale-android -it tailscale-android-shell-amd64
 
 .PHONY: docker-remove-shell-image
 docker-remove-shell-image: ## Removes all docker shell image

README.md

@@ -63,7 +63,7 @@ and XML files in Android Studio.  Enable "Format on Save".
 If you wish to avoid installing software on your host system, a Docker based development strategy is available, you can build and start a shell with:
 
 ```sh
-make dockershell
+make docker-shell
 ```
 
 Several other makefile recipes are available for setting up the proper build environment and running builds.