Doc error - TokenAwareHostPolicy does not exist

[fee-mendes]

We have received an inquiry in field due to README.md mentioning the existence of a TokenAwareHostPolicy which is misleading and the driver has no references to that:

java-driver$ grep -r tokenAwareHostPolicy
README.md:* Like all Scylla Drivers, the Scylla Java Driver is **Shard Aware** and contains extensions for a `tokenAwareHostPolicy`. 

It should be written as TokenAwarePolicy.