I've created my own validation rule phonePL in
app/design/frontend/Me/myskin/Magento_Ui/web/js/lib/validation/rules.js
I can activate it in
Magento/Checkout/view/frontend/layout/checkout_index_index.xml
By adding my validation rule in telephone item like so:
<item name="telephone" xsi:type="array">
<item name="config" xsi:type="array">
<item name="validation" xsi:type="array">
<item name="phonePL" xsi:type="string">true</item>
</item>
<item name="tooltip" xsi:type="array">
<item name="description" xsi:type="string" translate="true">For delivery questions.</item>
</item>
</item>
</item>
But how should I overwrite just this one telephone item in my theme? I dont want to do it directly in magento directory. I've got an xml file:
app/design/frontend/Me/myskin/Magento_Checkout/layout/checkout_index_index.xml
but I don't know what exactly should its structure look like?