add script for automatic generation of C# reference docs

src/csharp/doc/README.md

@@ -1,9 +1,28 @@
 DocFX-generated C# API Reference
 --------------------------------
 
+## Generating docs manually (on Windows)
+
 Install docfx based on instructions here: https://github.com/dotnet/docfx
 
 ```
 # generate docfx documentation into ./html directory
 $ docfx
 ```
+
+## Release process: script for regenerating the docs automatically
+
+After each gRPC C# release, the docs need to be regenerated
+and updated on the grpc.io site. The automated script will
+re-generate the docs (using dockerized docfx installation)
+and make everything ready for creating a PR to update the docs.
+
+```
+# 1. Run the script on Linux with docker installed
+$ ./generate_reference_docs.sh
+
+# 2. Enter the git repo with updated "gh-pages" branch
+$ cd grpc-gh-pages
+
+# 3. Review the changes and create a pull request
+```

src/csharp/doc/generate_reference_docs.sh

@@ -0,0 +1,38 @@
+#!/bin/sh
+# Copyright 2018 The gRPC Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Generates C# API docs using docfx inside docker.
+set -ex
+cd $(dirname $0)
+
+# cleanup temporary files
+rm -rf html obj grpc-gh-pages
+
+# generate into src/csharp/doc/html directory
+cd ..
+docker run --rm -v "$(pwd)":/work -w /work/doc --user "$(id -u):$(id -g)" -it tsgkadot/docker-docfx:latest docfx
+cd doc
+
+# prepare a clone of "gh-pages" branch where the generated docs are stored
+GITHUB_USER="${USER}"
+git clone -b gh-pages -o upstream git@github.com:grpc/grpc.git grpc-gh-pages
+cd grpc-gh-pages
+git remote add origin "git@github.com:${GITHUB_USER}/grpc.git"
+
+# replace old generated docs by the ones we just generated
+rm -r csharp
+cp -r ../html csharp
+
+echo "Done. Go to src/csharp/doc/grpc-gh-pages git repository and create a pull request to update the generated docs."