Add upload checklist item for plugin repository validation

Author: Xpirix

qgis-app/plugins/templates/plugins/form_snippet.html

@@ -126,6 +126,12 @@ <h4 class="title is-5">{% trans "Pre-upload Checklist" %}</h4>
         &nbsp;{% trans "My plugin ZIP file follows the correct QGIS plugin structure (e.g. a top-level folder containing <code>metadata.txt</code> and <code>__init__.py</code>)." %}
       </label>
     </div>
+    <div class="field">
+      <label class="checkbox">
+        <input type="checkbox" class="upload-checklist-item">
+        &nbsp;{% trans "The plugin repository is not empty and contains the same source code as the ZIP file, excluding compiled files (e.g. <code>__pycache__</code>)." %}
+      </label>
+    </div>
     <div class="field">
       <label class="checkbox">
         <input type="checkbox" class="upload-checklist-item">