The fonts can be added in app/fonts folder.

After you done that you will need to specify in your css (app/style.scss) the fonts path.

@font-face {
  font-family: 'icomoon';
  src:url('../fonts/icomoon.eot');
  src:url('../fonts/icomoon.eot?#iefix') format('embedded-opentype'),
  url('../fonts/icomoon.woff') format('woff'),
  url('../fonts/icomoon.ttf') format('truetype'),
  url('../fonts/icomoon.svg#icomoon') format('svg');
  font-weight: normal;
  font-style: normal;
}