docs: readme note for gke deployment configuration (#185)
docs: readme note for gke deployment configuration (#185)

* docs: note for gke deployment

This change contains a note for deployment in GKE. If no configuration
is provided the JVM in CoS detects only 1 CPU/Core, which restrain the
number of channels resulting in performance loss.

* docs: rephrased the readme notes

Added grpc thread sharing note

googleapis/java-bigtable,googleapis/java-bigtable,googleapis/java-bigtable