Added FOSSBilling to Money, Budgeting & Management (#4053)

Co-authored-by: Christoph Schläpfer <c.schlaepfer@datact.ch>
Co-authored-by: Kieran <32241933+KieranRobson@users.noreply.github.com>

README.md

@@ -1404,6 +1404,7 @@ _Related: [Inventory Management](#inventory-management), [Resource Planning - En
 - [Family Accounting Tool](https://github.com/nymanjens/facto) - Web-based finance management tool for partners with partially shared expenses. `Apache-2.0` `Scala`
 - [Fava](https://beancount.github.io/fava/) - Fava is the web frontend of Beancount, a text based double-entry accounting system. ([Demo](https://fava.pythonanywhere.com/example-with-budgets/income_statement/), [Source Code](https://github.com/beancount/fava)) `MIT` `Python`
 - [Firefly III](https://firefly-iii.org/) - Firefly III is a modern financial manager. It helps you to keep track of your money and make budget forecasts. It supports credit cards, has an advanced rule engine and can import data from many banks. ([Demo](https://demo.firefly-iii.org/), [Source Code](https://github.com/firefly-iii/firefly-iii)) `AGPL-3.0` `PHP`
+- [FOSSBilling](https://fossbilling.org/) - Free and open source hosting and billing automation. Integrates with WHM, CWP, cPanel and HestiaCP. Full API and easily extensible. ([Demo](https://fossbilling.org/demo), [Source Code](https://github.com/FOSSBilling/FOSSBilling)) `Apache-2.0` `PHP/Docker`
 - [Galette](https://galette.eu/dc/) - Galette is a membership management web application towards non profit organizations. ([Source Code](https://git.tuxfamily.org/galette/galette.git/)) `GPL-3.0` `PHP`
 - [Ghostfolio](https://ghostfol.io/) - Wealth management software to keep track of stocks, ETFs and cryptocurrencies. ([Source Code](https://github.com/ghostfolio/ghostfolio)) `AGPL-3.0` `Docker/Nodejs`
 - [GRR](https://grr.devome.com/?lang=en) - Assets management and booking for small/medium companies. ([Source Code](https://github.com/JeromeDevome/GRR)) `GPL-2.0` `PHP`