btn-admin-edit.php

<?php
//add function inside functions.php

//add wordpress dashicons frontend
add_action( 'wp_enqueue_scripts', 'load_dashicons_front_end' ); 
function load_dashicons_front_end() { 
    wp_enqueue_style( 'dashicons' ); 
}

//after create in your file single.php ou page.php add code echo <?php chr_edit_post(); ?:>
function chr_edit_post() {
	global $post;
    if ( is_user_logged_in() ) : ?>
        <div id="chr-edit-post">
            <dl>
                <dd><?php echo '<a href="' . esc_url( get_admin_url() ) . '" title="Acessar Backend" target="_blank"><span class="dashicons dashicons-wordpress"></span></a>'; ?></dd>
                <dd><?php echo '<a href="' . esc_url( get_edit_post_link( $post->ID ) ) . '" title="Editar Post - ' . get_the_title() . '" target="_blank"><span class="dashicons dashicons-edit-large"></span></a>'; ?></dd>
            </dl>
            <style type="text/css">
                #chr-edit-post{position: fixed; z-index: 9; right: 0; top: 50%; transform: translate(0, -50%);} 
                #chr-edit-post dl{flex-direction: column; display: flex; margin: 0; padding: 0;}
                #chr-edit-post dl dd{margin: .1rem 0;}
                #chr-edit-post dl dd a{ display: inline-block; text-decoration: none; color: #000; background-color: #29ce2b; padding: 1rem 1rem .5rem 1rem; transition: all .2s ease-in-out;} 
                #chr-edit-post dl dd a:hover{color: #FFF; background-color: #000;}
            </style>
        </div><?php
    endif;
}