🚢How to add custom fields to fulfillment email notification?

Edit the email notification template with this code snippet below.

<p>Hi {{ service_name }},</p>
<br>
<p>Please fulfill order {{ name }}.</p>
<p>Total number of items: {{ fulfillment.item_count }}</p>
<p>Unique items: {{ fulfillment.fulfillment_line_items.size }}</p>
<br>
<p><strong>Items to fulfill:</strong></p>

{% for line in fulfillment.fulfillment_line_items %}
  <p><strong>Item #{{ forloop.index }}:</strong></p>
  <p>Variant Title: {{ line.line_item.title }}</p>
  <p>SKU: {{ line.line_item.sku }}</p>
  <p>Quantity: {{ line.quantity }}</p>
  <p>Grams: {{ line.line_item.grams }}</p>
  <p>Vendor: {{ line.line_item.vendor }}</p>
  
  {% comment %}Added section for line item properties{% endcomment %}
  {% for property in line.line_item.properties %}
    {% assign property_first_char = property.first | slice: 0 %}
    {% if property.last != blank and property_first_char != '_' %}
      <p class="line-item-property">
        {{ property.first }}: {{ property.last }}
      </p>
    {% endif %}
  {% endfor %}
  
  <br>
{% endfor %}
{% if shipping_address %}
<br>
<p><strong>Shipping Address:</strong></p>
<p>{{ shipping_address.name }}{% if shipping_address.company %}
  {{ shipping_address.company }}{% endif %}</p>
<p>{{ shipping_address.address1 }}</p>
<p>{{ shipping_address.address2 }}</p>
<p>{{ shipping_address.city }}, {{ shipping_address.province }}</p>
<p>{{ shipping_address.zip }}</p>
<p>{{ shipping_address.country }}</p>
{% if shipping_address.phone %}<p>Phone: {{ shipping_address.phone }}</p>{% endif %}
{% endif %}
<br>
<p><strong>Shipping Method:</strong></p>
<p>{% if shipping_method %}{{ shipping_method.title }}{% else %}None{% endif %}</p>
<br>
<p><strong>Tracking Number:</strong></p>
<p>{% if fulfillment.tracking_number %}{{ fulfillment.tracking_number }}{% else %}None{% endif %}</p>
<br>
<p><strong>Customer Email:</strong></p>
<p>{{ email }}</p>
<br>
<p>Thank you,</p>
<p>{{ shop_name }}</p>