Fix livereload server startup bug

when I try to start the livereload server via `make livereload` I get the following error: "/bin/sh: 1: node_modules/make-livereload//node_modules/.bin/tiny-lr: not found"
The imported index.mk somehow can't reference the tiny-lr executable. I don't know if others have the same problem but the change I propose fixes the problem for me.