Add validation

Author: crissanclick

app/code/Magento/Customer/etc/adminhtml/system.xml

@@ -198,7 +198,8 @@
                 <field id="street_lines" translate="label comment" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="0" canRestore="1">
                     <label>Number of Lines in a Street Address</label>
                     <backend_model>Magento\Customer\Model\Config\Backend\Address\Street</backend_model>
-                    <comment>Leave empty for default (2). Valid range: 1-4</comment>
+                    <comment>Valid range: 1-4</comment>
+                    <validate>validate-digits validate-digits-range digits-range-1-4</validate>
                 </field>
                 <field id="prefix_show" translate="label comment" type="select" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="0">
                     <label>Show Prefix</label>