Add submodule instructions.
@@ -101,6 +101,7 @@ go get -u github.com/ry/v8worker2
cd $GOPATH/src/github.com/ry/v8worker2
./build.py --use_ccache
```
+Maybe also run `git submodule update --init` in the v8worker2 dir.
Finally you can get `deno` and its other Go deps.
