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

@@ -63,13 +63,13 @@ 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.
 
-Note that the docker makefile recipes s will preserve the image and remove container on completion. 
+Note that the docker makefile recipes s will preserve the image and remove container on completion.
-If changes are made to the build environment or toolchain, cached docker images may need to be rebuilt.  
+If changes are made to the build environment or toolchain, cached docker images may need to be rebuilt.
 The docker build image name is parameterized in the makefile and changing it provides a simple means to do this.
 
 ### Nix