Merge pull request #1161 from oneslash/documentation

(doc): add compression documentation part of #402

doc/compression.md

@@ -0,0 +1,31 @@
+# Compression
+
+## Client side
+The preferred method for configuring message compression on a client is to pass `options` when the client object is instantiated.
+
+These two options control compression behavior:
+
+**grpc.default_compression_algorithm** (int)
+
+Default compression algorithm for the channel, applies to sending messages.
+
+Possible values for this option are:
+- `0` - No compression
+- `1` - Compress with DEFLATE algorithm
+- `2` - Compress with GZIP algorithm
+- `3` - Stream compression with GZIP algorithm
+
+**grpc.default_compression_level** (int)
+
+Default compression level for the channel, applies to receiving messages.
+
+Possible values for this option are:
+- `0` - None
+- `1` - Low level
+- `2` - Medium level
+- `3` - High level
+
+### Code example
+```javascript
+client = new ExampleClient("example.com", credentials.createInsecure(), {'grpc.default_compression_algorithm': 2, 'grpc.default_compression_level': 2});
+```