Make security.png more descriptive

Access attempts to security.png are normally denied, so the name of the file will be more self-descriptive

inc/Ui/Admin.php

@@ -104,7 +104,7 @@ class Admin extends Ui {
         if(substr($conf['savedir'], 0, 2) !== './') return;
         echo '<a style="border:none; float:right;"
                 href="http://www.dokuwiki.org/security#web_access_security">
-                <img src="' . DOKU_URL . $conf['savedir'] . '/security.png" alt="Your data directory seems to be protected properly."
+                <img src="' . DOKU_URL . $conf['savedir'] . '/dont-panic-if-you-see-this-in-your-logs-it-means-your-directory-permissions-are-correct.png" alt="Your data directory seems to be protected properly."
                 onerror="this.parentNode.style.display=\'none\'" /></a>';
     }
 

install.php

@@ -110,7 +110,7 @@ header('Content-Type: text/html; charset=utf-8');
                 print "</div>\n";
             }
         ?>
-        <a style="background: transparent url(data/security.png) left top no-repeat;
+        <a style="background: transparent url(data/dont-panic-if-you-see-this-in-your-logs-it-means-your-directory-permissions-are-correct.png) left top no-repeat;
                   display: block; width:380px; height:73px; border:none; clear:both;"
            target="_blank"
            href="http://www.dokuwiki.org/security#web_access_security"></a>