docs: Add quotes around $PWD (#247)

Author: kroese

readme.md

@@ -49,7 +49,7 @@ services:
 ##### Via Docker CLI:
 
 ```bash
-docker run -it --rm --name macos -p 8006:8006 --device=/dev/kvm --device=/dev/net/tun --cap-add NET_ADMIN -v ${PWD:-.}/macos:/storage --stop-timeout 120 dockurr/macos
+docker run -it --rm --name macos -p 8006:8006 --device=/dev/kvm --device=/dev/net/tun --cap-add NET_ADMIN -v "${PWD:-.}/macos:/storage" --stop-timeout 120 dockurr/macos
 ```
 
 ##### Via Kubernetes: