docs: adding info about gRPC compression

Author: vlastahajek

README.md

@@ -175,6 +175,12 @@ try (Stream<PointValues> stream = client.queryPoints(sql1, QueryOptions.DEFAULTS
 
 System.out.printf("--------------------------------------------------------%n%n");
 ```
+## gRPC Compression
+
+The Java client supports gRPC response compression.
+
+If the server chooses to compress query responses (e.g., with gzip), the client
+will automatically decompress them — no extra configuration is required.
 
 ## Feedback