add information about recommended minimum response size for gzip, closes influxdata/DAR#284 (#3973)

content/influxdb/v2.2/query-data/execute-queries/influx-api.md

@@ -28,6 +28,12 @@ In your request, set the following:
 
 To compress the query response, set the `Accept-Encoding` header to `gzip`.
 This saves network bandwidth, but increases server-side load.
+
+We recommend only using gzip compression on responses that are larger than 1.4 KB.
+If the response is smaller than 1.4 KB, gzip encoding will always return a 1.4 KB
+response, despite the uncompressed response size.
+1500 bytes (~1.4 KB) is the maximum transmission unit (MTU) size for the public
+network and is the largest packet size allowed at the network layer.
 {{% /note %}}
 
 #### Flux - Example query request