Add link to get OM using Obtainium

Signed-off-by: Alexander Borsuk <[email protected]>

README.md

@@ -6,10 +6,11 @@
 It uses crowd-sourced [OpenStreetMap](https://www.openstreetmap.org) data and is developed with love by the creators of **MapsWithMe** (later renamed to **Maps.Me**) and by our community.
 No ads, no tracking, no data collection, no crapware. Your [donations](https://organicmaps.app/donate/) and positive reviews motivate and inspire us, thanks ❤️!
 
-[<img src="docs/badges/apple-appstore.png" alt="App Store" width="180">](https://apps.apple.com/app/organic-maps/id1567437057)
-[<img src="docs/badges/google-play.png" alt="Google Play" width="180">](https://play.google.com/store/apps/details?id=app.organicmaps)
-[<img src="docs/badges/huawei-appgallery.png" alt="AppGallery" width="180">](https://appgallery.huawei.com/#/app/C104325611)
-[<img src="docs/badges/fdroid.png" alt="F-Droid" width="180">](https://f-droid.org/en/packages/app.organicmaps/)
+[<img src="docs/badges/apple-appstore.png" alt="App Store" width="160">](https://apps.apple.com/app/organic-maps/id1567437057)
+[<img src="docs/badges/google-play.png" alt="Google Play" width="160">](https://play.google.com/store/apps/details?id=app.organicmaps)
+[<img src="docs/badges/huawei-appgallery.png" alt="AppGallery" width="160">](https://appgallery.huawei.com/#/app/C104325611)
+[<img src="docs/badges/obtainium.png" alt="Obtainium" width="160">](https://github.com/organicmaps/organicmaps/wiki/Installing-Organic-Maps-from-GitHub-using-Obtainium)
+[<img src="docs/badges/fdroid.png" alt="F-Droid" width="160">](https://f-droid.org/en/packages/app.organicmaps/)
 
 <p float="left">
   <img src="android/app/src/fdroid/play/listings/en-US/graphics/phone-screenshots/1.jpg" width="400" />