I',m sorry if this is out of topic. I don't know where to report this.
I suggest to update the helloworld tutorial:
Adding this after the initial:
make distclean in chapter1: https://openwrt.org/docs/guide-developer/helloworld/chapter1
./scripts/feeds update -a ./scripts/feeds install -a
Also, the arrows to move NEXT or PREVIOUS in some of the chapters are missing...