feat: extend docs with mirror back layers

Author: hauserkristof

web/help.html

@@ -49,6 +49,11 @@ <h2>Drills</h2>
         Affinity and KiCAD.
       </p>
 
+      <h2>Mirror back layers</h2>
+      <p>Gingerbread allows you to mirror the <code>B.SilkS</code>, <code>B.Mask</code>, and <code>B.Cu</code> layers so that the it is correctly mirrored in the output. This can be switched
+        off if you don't want this behavior.</p>
+
+
       <h2>Exporting your design</h2>
       <p>When exporting you design to an SVG for Gingerbread, click the <strong>More</strong> button and setup the export parameters as shown below so that "Rasterize" is set to
         "Nothing", "Export text as curves" is checked, and "Flatten transforms" is checked.</p>

web/index.html

@@ -129,7 +129,7 @@
           <div class="field">
             <label class="checkbox">
               <input type="checkbox" x-model="design.mirror_back_layers">
-              Mirror back layers (3)
+              Mirror back layers
             </label>
           </div>