Add clean script

clean.sh

@@ -0,0 +1,33 @@
+#!/bin/bash
+# A script to clean all examples.
+# Run this script from the root directory of the workshop repository.
+
+# Clean the auction example.
+cd auction
+leo clean
+cd ..
+
+# Clean the basic bank example.
+cd basic_bank
+leo clean
+cd ..
+
+# Clean the battleship example.
+cd battleship
+leo clean
+cd ..
+
+# Clean the tictactoe example.
+cd tictactoe
+leo clean
+cd ..
+
+# Clean the token example.
+cd token
+leo clean
+cd ..
+
+# Clean the vote example.
+cd vote
+leo clean
+cd ..