Add feature gates realted to streaming collections

Author: tengqm

content/en/docs/reference/command-line-tools-reference/feature-gates/StreamingCollectionEncodingToJSON.md

@@ -0,0 +1,14 @@
+---
+title: StreamingCollectionEncodingToJSON
+content_type: feature_gate
+_build:
+  list: never
+  render: false
+
+stages:
+  - stage: alpha 
+    defaultValue: true
+    fromVersion: "1.33"
+
+---
+Allow the API server JSON encoder to encode collections item by item, instead of all at once.

content/en/docs/reference/command-line-tools-reference/feature-gates/StreamingCollectionEncodingToProtobuf.md

@@ -0,0 +1,14 @@
+---
+title: StreamingCollectionEncodingToProtobuf
+content_type: feature_gate
+_build:
+  list: never
+  render: false
+
+stages:
+  - stage: alpha 
+    defaultValue: true
+    fromVersion: "1.33"
+
+---
+Allow the API server Protobuf encoder to encode collections item by item, instead of all at once.