Remove SolidInvoice homepage link (HTTP 530)

- ref. #3558 
- `https://solidinvoice.co : HTTP 530`
- ` Error 1033 Argo Tunnel error - You've requested a page on a website (solidinvoice.co) that is on the Cloudflare network. The host (solidinvoice.co) is configured as an Argo Tunnel, and Cloudflare is currently unable to resolve it.`

README.md

@@ -1418,7 +1418,7 @@ _Related: [Inventory Management](#inventory-management), [Resource Planning - En
 - [OpenBudgeteer](https://github.com/TheAxelander/OpenBudgeteer) - A budgeting app based on the Bucket Budgeting Principle. `MIT` `Docker/C#`
 - [REI3](https://rei3.de/home_en/) - Open source, expandable Business Management Software. Manage tasks, time, assets and much more. ([Demo](https://rei3.de/demo_en/), [Source Code](https://github.com/r3-team/r3)) `MIT` `Go`
 - [SilverStrike](https://silverstrike.org/) - Personal finance management made easy. ([Demo](https://demo.silverstrike.org/), [Source Code](https://github.com/agstrike/silverstrike)) `MIT` `Python/Django`
-- [SolidInvoice](https://solidinvoice.co) - Open source invoicing and quote application. ([Source Code](https://github.com/SolidInvoice/SolidInvoice)) `MIT` `PHP`
+- [SolidInvoice]([https://solidinvoice.co](https://github.com/SolidInvoice/SolidInvoice)) - Open source invoicing and quote application. `MIT` `PHP`
 
 
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