Add I, Librarian to Document Management

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- [x] Additions are inserted preserving alphabetical order.
- [x] Additions are not already listed at any of
  - [awesome-sysadmin](https://github.com/n1trux/awesome-sysadmin) (IT infrastructure management),
  - [awesome-analytics](https://github.com/onurakpolat/awesome-analytics) (analytics),
  - [staticgen.com](https://www.staticgen.com/)
  - [staticsitegenerators.net](https://staticsitegenerators.net/) (static site generators).
- [x] The `Language` tag is the main server-side requirement for the software - don't include frameworks or specific dialects.
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- [ ] Any category you are creating has the minimum requirement of 3 items.
  If not, your addition may be inserted into `Misc/Other`.
- [x] Any software project you are adding to the list is actively maintained.
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README.md

@@ -618,6 +618,7 @@ _See https://github.com/n1trux/awesome-sysadmin#dns_
 - [Docspell](https://docspell.org) - Auto-tagging document organizer and archive. ([Source Code](https://github.com/eikek/docspell)) `GPL-3.0` `Scala/Java`
 - [EdPaper](https://github.com/Edraens/EdPaper) - PDF organizer with users management. `MIT` `PHP`
 - [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`
+- [I, Librarian](https://i-librarian.net) - I, Librarian can organize PDF papers and office documents. It provides a lot of extra features for students and research groups both in industry and academia. ([Demo](https://i-librarian.net/demo/), [Source Code](https://github.com/mkucej/i-librarian-free)) `GPL-3.0` `PHP`
 - [Mayan EDMS](http://www.mayan-edms.com) - Free Open Source Electronic Document Management System. An electronic vault for your documents with preview generation, OCR, and automatic categorization among other features. ([Source Code](https://gitlab.com/mayan-edms/mayan-edms)) `Apache-2.0` `Python`
 - [Papermerge](https://www.papermerge.com) - Open Source Document Management System focused on scanned documents (electronic archives). Features file browsing in similar way to dropbox/google drive. OCR, full text search, text overlay/selection. ([Source Code](https://github.com/ciur/papermerge)) `Apache-2.0` `Python`
 - [Paperless](https://github.com/the-paperless-project/paperless) - Scan, index, and archive all of your paper documents. `GPL-3.0` `Python`