Question: How to pick the optimal number of shards?

I see that the config allows for specifying the number of shards. In [your article](https://allegro.tech/2016/03/writing-fast-cache-service-in-go.html) about the idea behind bigcache, I see some information on how the shards are used. However, I am wondering if you can provide any advice on how to pick the right number of shards. I understand this is probably heavily dependent on how big the cache is, but some guidelines would be amazing. Perhaps this could be included in the README?