Adds a hint to the first and last name fields at checkout.

my_pmpro_add_name_checkout_hints.php

<?php

// Copy from below here

function my_pmpro_add_name_checkout_hints() {
	?>
		<script>
		jQuery("#bfirstname").parent().append("<p><small class='lite'>I am a hint for first name.</small></p>");
		jQuery("#blastname").parent().append("<p><small class='lite'>I am a hint for last name.</small></p>");
		</script>
	<?php
}
add_action( 'pmpro_checkout_after_billing_fields', 'my_pmpro_add_name_checkout_hints' );