ustify-contenido: flex-end
<div class="d-flex justify-content-end">...</div>
justify-content-between bootstrap 4
<div class="d-flex justify-content-start">...</div>
<div class="d-flex justify-content-end">...</div>
<div class="d-flex justify-content-center">...</div>
<div class="d-flex justify-content-between">...</div>
<div class="d-flex justify-content-around">...</div>
pantalla de arranque flex
<div class="d-flex">I'm a flexbox container!</div>
justificar el espacio de contenido entre la clase bootstrap
<div class="row d-flex justify-content-between"></div>