Embed a Gist in WordPress using a shortcode.

wp_gist_embed.php

<?php
/**
 * Create the shortcode to embed a Gist.
 *
 * @example [gist]https://gist.github.com/aldolat/8625342[/gist]
 * @since 4.5
 */
function aldolat_gist_embed( $atts, $content = null ) {
	extract( shortcode_atts( array(), $atts ) );

	$output = '<script src="' . esc_url( $content, 'https' ) . '.js"></script>';

	return $output;
}
add_shortcode( 'gist', 'aldolat_gist_embed' );