Update README.md

[byinarie]

fix npm build syntax

npm build
Unknown command: "build"

Did you mean this?
    npm run build # run the "build" package script

To see a list of supported npm commands, run:
  npm help

npm run build

> [email protected] build
> ng build

✔ Browser application bundle generation complete.
✔ Copying assets complete.
✔ Index html generation complete.