[docs] use relative links in V9LicenseUpgradeWarning

Author: aemartos

docs/src/modules/components/V9LicenseUpgradeWarning.js

@@ -12,13 +12,11 @@ export default function V9LicenseUpgradeWarning() {
         <div className="MuiCallout-content">
           <p>
             If you&apos;re upgrading from v8 to v9, you&apos;ll need to generate a new license key
-            from your <a href="https://mui.com/r/x-license-account/">MUI Store account</a>. The new
-            v9 key inherits the same expiration date as your existing v8 key, so there&apos;s no
-            extra cost during your current term. See{' '}
-            <a href="https://mui.com/r/x-license-key-upgrade/">
-              How can I generate a v9 license key?
-            </a>{' '}
-            for step-by-step instructions.
+            from your <a href="/r/x-license-account/">MUI Store account</a>. The new v9 key inherits
+            the same expiration date as your existing v8 key, so there&apos;s no extra cost during
+            your current term. See{' '}
+            <a href="/r/x-license-key-upgrade/">How can I generate a v9 license key?</a> for
+            step-by-step instructions.
           </p>
           <p>
             When it&apos;s time to renew, you&apos;ll need to choose which key to renew, note that