Added example for get_key_digest() API
Added example for get_key_digest() API

trupty/aerospike-client-python,arthurprs/aerospike-client-python,arthurprs/aerospike-client-python,aerospike/aerospike-client-python,arthurprs/aerospike-client-python,aerospike/aerospike-client-python,trupty/aerospike-client-python,trupty/aerospike-client-python,aerospike/aerospike-client-python