remove invoiceplane main link/demo, replace with source code link - website is gone

README.md

@@ -1032,7 +1032,7 @@ See also https://github.com/n1trux/awesome-sysadmin#it-asset-management
 - [Hospital Run](http://hospitalrun.io/) - Hospital Run is offline enabled hospital management software. ([Source Code](https://github.com/HospitalRun/hospitalrun-server), [Demo](http://hospitalrun.io/demo/)) `GPL-3.0` `Nodejs`
 - [Inventaire](https://inventaire.io/welcome) - Collaborative resources mapper project, while yet only focused on exploring books mapping with wikidata and ISBNs. ([Source Code](https://github.com/inventaire/inventaire)) `AGPL-3.0` `Nodejs`
 - [Invoice Ninja](https://www.invoiceninja.org/) - Powerful tool to invoice clients online. ([Demo](https://app.invoiceninja.com/invoices/create), [Source Code](https://github.com/invoiceninja/invoiceninja)) `AAL` `PHP`
-- [InvoicePlane](https://invoiceplane.com/) - Manage quotes, invoices, payments and customers for your small business. ([Demo](https://demo.invoiceplane.com), [Source Code](https://github.com/InvoicePlane/InvoicePlane)) `MIT` `PHP`
+- [InvoicePlane](https://github.com/InvoicePlane/InvoicePlane) - Manage quotes, invoices, payments and customers for your small business. `MIT` `PHP`
 - [IHateMoney](http://ihatemoney.org/) - Manage your shared expenses, easily. ([Demo](https://ihatemoney.org/demo/), [Source Code](https://github.com/spiral-project/ihatemoney)) `BSD-3-Clause` `Python`
 - [Kresus](https://kresus.org/) - Open source personal finance manager. ([Demo](https://kresus.org/en/demo.html), [Source Code](https://github.com/kresusapp/kresus)) `MIT` `Nodejs`
 - [OnTrack](https://github.com/inoda/ontrack) - A simple app to track spend and set goals. `MIT` `Ruby/React`