Fix XH sponsor link in README.md (#4591)

Author: amcclain

README.md

@@ -48,7 +48,7 @@ MobX is made possible by the generosity of the sponsors below, and many other [i
 **🥈 Silver sponsors (\$500+ total contributions):**<br/>
 
 <a href="https://mantro.net/jobs/warlock"><img src="https://mobx.js.org/assets/mantro.png" align="center" width="100" title="mantro GmbH" alt="mantro GmbH"></a>
-<a href="https://www.xh.com/"><img src="https://mobx.js.org/assets/xh.png" align="center" width="100" title="Extremely Heavy" alt="Extremely Heavy" /></a>
+<a href="https://xh.io/"><img src="https://mobx.js.org/assets/xh.png" align="center" width="100" title="Extremely Heavy Industries" alt="Extremely Heavy Industries" /></a>
 <a href="https://www.algolia.com/"><img src="https://mobx.js.org/assets/algolia.jpg" align="center" width="100" title="Algolia" alt="Algolia" /></a>
 <a href="https://space307.com/?utm_source=sponsorship&utm_medium=mobx&utm_campaign=readme"><img src="https://mobx.js.org/assets/space307.png" align="center" width="100" title="Space307" alt="Space307"/></a>
 <a href="https://blokt.com/"><img src="https://mobx.js.org/assets/blokt.jpg" align="center" width="100" title="Blokt" alt="Blokt"/></a>