Fix typo in string

Author: jaapmarcus

web/templates/pages/add_dns.html

@@ -81,7 +81,7 @@ <h1 class="form-title"><?=_('Adding DNS Domain');?></h1>
             <div class="form-check u-mb10">
               <input class="form-check-input" type="checkbox" name="v_dnssec" id="v_dnssec" value="yes" <?php if($v_dnssec === 'yes'){ echo ' checked'; } ?>>
               <label for="v_dnssec">
-                <?=_('Enable DNSEC');?>
+                <?=_('Enable DNSSEC');?>
               </label>
             </div>
             <div class="u-mb10">

web/templates/pages/edit_dns.html

@@ -66,7 +66,7 @@ <h1 class="form-title"><?=_('Editing DNS Domain');?></h1>
         <div class="form-check u-mb10">
           <input class="form-check-input" type="checkbox" name="v_dnssec" id="v_dnssec" value="yes" <?php if($v_dnssec === 'yes'){ echo ' checked'; } ?>>
           <label for="v_dnssec">
-            <?=_('Enable DNSEC');?>
+            <?=_('Enable DNSSEC');?>
           </label>
         </div>
         <div class="u-mb10">