Added Architectural Metapatterns (#11800)

* Added Architectural Metapatterns

* One link per listing

books/free-programming-books-subjects.md

@@ -890,6 +890,7 @@ Kerridge (PDF) (email address *requested*, not required)
 
 * [A Primer on Design Patterns](https://leanpub.com/aprimerondesignpatterns/read) - Rahul Batra (HTML)
 * [Agile Planning: From Ideas to Story Cards](https://launchschool.com/books/agile_planning) - Launch School
+* [Architectural Metapatterns: The Pattern Language of Software Architecture](https://github.com/denyspoltorak/publications/tree/main/ArchitecturalMetapatterns) - Denys Poltorak (PDF, EPUB, DOCX) (CC BY)
 * [Architectural Styles and the Design of Network-based Software Architectures](https://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm) - Roy Thomas Fielding
 * [Best Kept Secrets of Peer Code Review](https://smartbear.com/lp/ebook/collaborator/secrets-of-peer-code-review/)
 * [Building Secure & Reliable Systems](https://static.googleusercontent.com/media/landing.google.com/en//sre/static/pdf/Building_Secure_and_Reliable_Systems.pdf) - Heather Adkins, Betsy Beyer, Paul Blankinship, Piotr Lewandowski, Ana Oprea, Adam Stubblefield (PDF)