refactor(kb/postgres): group related articles into a dedicated folder

knowledge base/postgresql/pgadmin.md

@@ -0,0 +1,66 @@
+# pgAdmin
+
+Browser-based management tool for [PostgreSQL].
+
+1. [TL;DR](#tldr)
+1. [Further readings](#further-readings)
+   1. [Sources](#sources)
+
+## TL;DR
+
+<details>
+  <summary>Setup</summary>
+
+```sh
+brew install --cask 'pgadmin4'
+docker pull 'dpage/pgadmin4'
+```
+
+</details>
+
+<!-- Uncomment if used
+<details>
+  <summary>Usage</summary>
+
+```sh
+```
+
+</details>
+-->
+
+<!-- Uncomment if used
+<details>
+  <summary>Real world use cases</summary>
+
+```sh
+```
+
+</details>
+-->
+
+## Further readings
+
+- [PostgreSQL]
+- [Website]
+- [Codebase]
+
+### Sources
+
+- [Documentation]
+
+<!--
+  Reference
+  ═╬═Time══
+  -->
+
+<!-- In-article sections -->
+<!-- Knowledge base -->
+[PostgreSQL]: README.md
+
+<!-- Files -->
+<!-- Upstream -->
+[codebase]: https://github.com/pgadmin-org/pgadmin4
+[documentation]: https://www.pgadmin.org/docs/
+[website]: https://www.pgadmin.org/
+
+<!-- Others -->