Enable SVG file upload through WordPress Media Uploader

add-svg-upload.php

<?php

/**
 * Add the SVG Mime type to the uploader
 * @author Alain Schlesser (alain.schlesser@gmail.com)
 *
 * @param  array  $mimes  list of mime types that are allowed by the
 *                        WordPress uploader
 * @return array          modified version of the $mimes array
 *
 * @see https://codex.wordpress.org/Plugin_API/Filter_Reference/upload_mimes
 * @see http://www.w3.org/TR/SVG/mimereg.html
 */
function as_svg_mime_type( $mimes ) {

	// add official SVG mime type definition to the array of allowed mime types
	$mimes['svg'] = 'image/svg+xml';

	// return the modified array
	return $mimes;
}
add_filter( 'upload_mimes', 'as_svg_mime_type' );