Add crc32c to README and docs

Author: dpkp

README.rst

@@ -142,6 +142,14 @@ To enable snappy compression/decompression install python-snappy (also requires
 See <https://kafka-python.readthedocs.io/en/master/install.html#optional-snappy-install>
 for more information.
 
+Optimized CRC32 Validation
+**************************
+
+Kafka uses CRC32 checksums to validate messages. kafka-python includes a pure
+python implementation for compatibility. To improve performance for high-throughput
+applications, kafka-python will use `crc32c` for optimized native code if installed.
+See https://pypi.org/project/crc32c/
+
 Protocol
 ********
 

docs/install.rst

@@ -31,6 +31,14 @@ To enable LZ4 compression/decompression, install python-lz4:
 >>> pip install lz4
 
 
+Optional crc32c install
+********************
+
+To enable optimized CRC32 checksum validation, install crc32c:
+
+>>> pip install crc32c
+
+
 Optional Snappy install
 ***********************