Fix typo in on_docker.md (#3477)

gitbook/basics/getting-started/on_docker.md

@@ -14,8 +14,8 @@ make
 Then you are ready to go to the directory that contains the hello world program and copy our iwasm vmcore
 
 ```sh
-cp iwasm ../../app-samples/hello-world
-cd ../../app-samples/hello-world
+cp iwasm ../../../app-samples/hello-world
+cd ../../../app-samples/hello-world
 ./build.sh
 ```