Added Postman's notes to the knowledge base

knowledge base/postman.md

@@ -0,0 +1,18 @@
+# Postman <!-- omit in toc -->
+
+API platform for building and using APIs.
+
+## Further readings
+
+- [Website]
+- [Documentation]
+- [Insomnia], an alternative to Postman
+- [Newman], CLI Collection runner for Postman
+
+<!-- internal knowledge base -->
+[insomnia]: insomnia.md
+[newman]: newman.md
+
+<!-- projects' references -->
+[documentation]: https://learning.postman.com/docs
+[website]: https://www.postman.com/