Added hyperlink to app on Flathub

Author: andrewmurphy353

README.md

@@ -24,7 +24,7 @@ The distributions include:
 ## Installation
 
 ### Linux (Flatpak)
-Install Curo Calculator via Flathub:
+Install [Curo Calculator](https://flathub.org/en/apps/app.curocalc.calculator) via Flathub:
 ```
 flatpak install flathub app.curocalc.calculator
 ```
@@ -55,4 +55,4 @@ This repository is structured to meet Flathub requirements:
 - Metadata files (`app.curocalc.calculator.yml`, `app.curocalc.calculator.desktop`, `app.curocalc.calculator.metainfo.xml`) are provided under MIT; the icon (`app.curocalc.calculator.svg`) is proprietary.
 - Builds use Flathub-hosted runtimes with no end-of-life dependencies.
 - OARS content rating: Safe for general audiences (no violence, etc.).
-- Screenshots: Included in `app.curocalc.calculator.metainfo.xml` with direct URLs.
+- Screenshots: Included in `app.curocalc.calculator.metainfo.xml` with direct URLs.