docs: update license from AGPL to PMPL

- Replace AGPL-3.0-or-later with PMPL-1.0-or-later
- Update license name and URLs
- Align with palimpsest-license standard

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Your Name

README.adoc

@@ -242,7 +242,7 @@ vext/
 
 == License
 
-Dual-licensed under MIT OR AGPL-3.0-or-later (Palimpsest licensing).
+Dual-licensed under MIT OR PMPL-1.0-or-later (Palimpsest licensing).
 
 Choose the license that works best for your use case.