Adding two additional sponsor slots to balance out the grid.

Author: davedbase

README.md

@@ -218,3 +218,5 @@ Become a sponsor and get your logo on our README on GitHub with a link to your s
 <a href="https://opencollective.com/solid/sponsor/8/website" target="_blank"><img src="https://opencollective.com/solid/sponsor/8/avatar.svg"></a>
 <a href="https://opencollective.com/solid/sponsor/9/website" target="_blank"><img src="https://opencollective.com/solid/sponsor/9/avatar.svg"></a>
 <a href="https://opencollective.com/solid/sponsor/10/website" target="_blank"><img src="https://opencollective.com/solid/sponsor/10/avatar.svg"></a>
+<a href="https://opencollective.com/solid/sponsor/11/website" target="_blank"><img src="https://opencollective.com/solid/sponsor/11/avatar.svg"></a>
+<a href="https://opencollective.com/solid/sponsor/12/website" target="_blank"><img src="https://opencollective.com/solid/sponsor/12/avatar.svg"></a>