add description for document management category

- https://github.com/awesome-selfhosted/awesome-selfhosted/issues/2984

README.md

@@ -738,6 +738,8 @@ _See also: [awesome-sysadmin/DNS](https://github.com/awesome-foss/awesome-sysadm
 
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+A [document management system](https://en.wikipedia.org/wiki/Document_management_system) (DMS) is a system used to receive, track, manage and store documents and reduce paper.
+
 - [DOCAT](https://github.com/docat-org/docat) - Host your docs. Simple. Versioned. Fancy. `MIT` `Python/Docker`
 - [Docspell](https://docspell.org) - Auto-tagging document organizer and archive. ([Source Code](https://github.com/eikek/docspell)) `GPL-3.0` `Scala/Java`
 - [EveryDocs](https://github.com/jonashellmann/everydocs-core) - A simple Document Management System for private use with basic functionality to organize your documents digitally. `GPL-3.0` `Ruby`