Improve usage section of readme

README.md

@@ -9,15 +9,29 @@
 
 A fully pre-configured Ledger SDK build environment.
 
+<p align="center">
+	<img src="demo.svg" width="720">
+</p>
+
 ## Usage
 
+To run `make` in your `~/code/my-ledger-app` project dir:
+
 ```
 docker run -v ~/code/my-ledger-app:/code lukechilds/ledger-sdk
 ```
 
-<p align="center">
-	<img src="demo.svg" width="720">
-</p>
+If you're already in your project dir you can just do:
+
+```
+docker run -v ${PWD}:/code lukechilds/ledger-sdk
+```
+
+To run an arbitrary command in your project dir:
+
+```
+docker run -v ${PWD}:/code lukechilds/ledger-sdk 'make clean'
+```
 
 ## License