document gRPC proxy env var

pongad · web-flow · commit bbb9c3034547 · 2017-06-21T08:53:41.000+10:00
Updates #2161.
diff --git a/README.md b/README.md
@@ -835,6 +835,13 @@ Troubleshooting
 
 To get help, follow the instructions in the [shared Troubleshooting document](https://github.com/GoogleCloudPlatform/gcloud-common/blob/master/troubleshooting/readme.md#troubleshooting).
 
+### Proxy (Experimental)
+Many clients in this repository use gRPC, not HTTP.
+In these clients, the `http.proxyHost` property takes no effect.
+To use proxy in gRPC clients, set the `GRPC_PROXY_EXP` environment variable;
+more details are available in the gRPC [release note](https://github.com/grpc/grpc-java/releases/tag/v1.0.3).
+Please note that proxy support is currently experimental.
+
 Java Versions
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