Merge pull request #3082 from replicatedhq/expires-at-format

explain midnight is at the beginning of the day

Author: paigecalvert

docs/vendor/licenses-about.mdx

@@ -169,7 +169,7 @@ For information about how to use the SDK API to query license entitlements at ru
 
 ### License Expiration Handling {#expiration}
 
-The built-in `expires_at` license field defines the expiration date for a customer license. When you set an expiration date in the Vendor Portal, the `expires_at` field is set to midnight UTC on the date selected.
+The built-in `expires_at` license field defines the expiration date for a customer license. When you set an expiration date in the Vendor Portal, the `expires_at` field is encoded in ISO 8601 format (`2026-01-23T00:00:00Z`) and is set to midnight UTC at the beginning of the calendar day (`00:00:00`) on the date selected.
 
 Replicated enforces the following logic when a license expires:
 * By default, instances with expired licenses continue to run.

docs/vendor/licenses-using-builtin-fields.mdx

@@ -96,7 +96,7 @@ The built-in license fields are reserved field names.
     </tr>
     <tr>
       <td>`expires_at`</td>
-      <td><p>Defines the expiration date for the license. The date is encoded in ISO 8601 format (`2026-01-23T00:00:00Z`) and is set to midnight UTC on the date selected. If a license does not expire, this field is missing.</p><p>For information about the default behavior when a license expires, see [License Expiration Handling](licenses-about#expiration) in _About Customers_.</p></td>
+      <td><p>Defines the expiration date for the license. The date is encoded in ISO 8601 format (`2026-01-23T00:00:00Z`) and is set to midnight UTC at the beginning of the calendar day (`00:00:00`) on the date selected. If a license does not expire, this field is missing.</p><p>For information about the default behavior when a license expires, see [License Expiration Handling](licenses-about#expiration) in _About Customers_.</p></td>
     </tr>
     <tr>
       <td>`licenseSequence`</td>