README.md: Make avro install example work with csh (@andreyferriyan, #668)

andreyferriyan · edenhill · commit d56ea3eb875a · 2019-09-19T14:38:01.000+02:00
diff --git a/README.md b/README.md
@@ -196,7 +196,7 @@ Install
 
 **Install AvroProducer and AvroConsumer:**
 
-    $ pip install confluent-kafka[avro]
+    $ pip install "confluent-kafka[avro]"
 
 **Install from source from PyPi** *(requires librdkafka + dependencies to be installed separately)*:
 
