Add book Azure for Architects (#3812)

* Add book Azure for Architects

* Update free-programming-books.md

free-programming-books.md

@@ -360,6 +360,7 @@
 
 #### Cloud Computing
 
+* [Azure for Architects, Third Edition](https://azure.microsoft.com/en-us/resources/azure-for-architects/) (PDF) *(email address or account required)*
 * [Azure Functions Succinctly, Syncfusion](https://www.syncfusion.com/ebooks/azure-functions-succinctly) (PDF, Kindle) (email address requested, not required)
 * [Cloud Computing for Science and Engineering](https://cloud4scieng.org/chapters/) - Ian Foster, Dennis B. Gannon (:construction: *in process*)
 * [Cloud Design Patterns](https://www.microsoft.com/en-us/download/details.aspx?id=42026)