Change description of my Jetpack facebook shared links [closed]

This part comes from the function comment_form() which is called by your theme, probably in comments.php:

'comment_notes_after'  => '<p class="form-allowed-tags">' 
    . sprintf( __( 
    'You may use these <abbr title="HyperText Markup Language">HTML</abbr> tags 
    and attributes: %s' ), ' <code>' . allowed_tags() . '</code>' ) 
    . '</p>',

You can filter it out with a simple plugin:

<?php
/*
Plugin Name: Remove Markup Notice on Comment Form
*/
add_filter( 'comment_form_defaults', 'wpse_41181_remove_markup_notice', 10, 1 );

function wpse_41181_remove_markup_notice( $strings )
{
    $strings['comment_notes_after'] = '';
    return $strings;
}

How you get a better description … I don’t know. I’m sure there is a FAQ for that available. Aren’t there settings in /wp-admin/ for this module?