add gitpod support (apache#1265)

.gitmodules

@@ -4,4 +4,4 @@
 	url = https://github.com/google/docsy.git
 [submodule ".github/themes/docsy"]
 	path = .github/themes/docsy
-	url = git@github.com:google/docsy.git
+	url = https://github.com/google/docsy.git

.gitpod.yml

@@ -0,0 +1,31 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+# List the start up tasks. Learn more https://www.gitpod.io/docs/config-start-tasks/
+tasks:
+  - name: Install dependency & Start hugo server
+    before: |
+      git submodule update --init --recursive
+      npm install
+      cd themes/docsy/ && npm install && cd ../../
+      npm install -g hugo-extended
+    command: hugo server --disableFastRender --bind=0.0.0.0 --port=1313 --baseURL=$(gp url 1313) --appendPort=false
+
+# List the ports to expose. Learn more https://www.gitpod.io/docs/config-ports/
+ports:
+  - port: 1313
+    onOpen: open-browser
+    visibility: public