auto password hash and add help_text in inputs

fastapi_admin/templates/widgets/inputs/json.html

@@ -2,6 +2,11 @@
 <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/jsoneditor@9.4.0/dist/jsoneditor.min.css">
 <div class="form-label">{{ label }}</div>
 <div id="{{ name }}" class="form-group mb-3"></div>
+{% if help_text %}
+    <small class="form-hint">
+        {{ help_text }}
+    </small>
+{% endif %}
 <input {% if not null %}required{% endif %} type="text" name="{{ name }}" value='{{ value|safe }}' hidden>
 <style>
     .jsoneditor {