Update README.md

Add in OSPOS

README.md

@@ -1303,6 +1303,7 @@ See also _[Monitoring](#monitoring)_
 - [LedgerSMB](https://ledgersmb.org/) - Integrated accounting and ERP system for small and midsize businesses, with double entry accounting, budgeting, invoicing, quotations, projects, orders and inventory management, shipping and more. ([Demo](https://demo.cloud.efficito.com/erp/1.5/login.pl), [Source Code](https://github.com/ledgersmb/LedgerSMB)) `GPL-2.0` `Perl`
 - [Odoo](http://odoo.com) - Free open source ERP system. ([Demo](https://demo.odoo.com/), [Source Code](https://github.com/odoo/odoo)) `LGPL-3.0` `Python`
 - [OFBiz](https://ofbiz.apache.org/) - FOSS enterprise resource planning system with a suite of business applications flexible enough to be used across any industry. ([Source Code](https://svn.apache.org/viewvc/ofbiz/)) `Apache-2.0` `Java`
+- [OSPOS](https://www.opensourcepos.org/) - Open Source Point of Sale is a web based point of sale system. ([Demo](https://demo.opensourcepos.org/), [Source Code](https://github.com/opensourcepos/opensourcepos)) `Other` `PHP`
 - [Tryton](http://www.tryton.org/) - Free open source business solution. ([Demo](http://www.tryton.org/download.html), [Source Code](https://hg.tryton.org/)) `GPL-3.0` `Python`
 
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