Homepage link fix

[jtedescojam]

1. A concise explanation of the problem you're experiencing.
Homepage link to Code Examples has an extra L:

CesiumJS

Links to:
https://cesiumjs.org/Cesium/Build/Apps/Sandcastle/index.htmll

When it should be:

Cesium Sandcastle

[Gabby_Getz]

Thanks for pointing that out! Fixing now.