Improve documentation for App Cache

The documentation for Local [Local Cache](https://learn.microsoft.com/en-us/azure/app-service/overview-local-cache) has a link to [App Cache](https://github.com/Azure-App-Service/KuduLite/wiki/App-Cache). The documentation for App Cache itself however is just one wiki page that was last touched in 2021. There are a some [github issues](https://github.com/Azure-App-Service/KuduLite/issues) about it, but none have been closed since 2021. Overall, there seems to be barely any activity on that github.

My issue is that from the current documentation, it is not clear to me if App Cache is really a supported feature. If not, the reference should be removed from the Local Cache page. If it is, documentation on it should be improved and ideally someone should keep an eye on the github issues for it.