update Docker info

conf/locale/locale_en-US.ini

@@ -53,6 +53,7 @@ code = Code
 [install]
 install = Installation
 title = Install Steps For First-time Run
+docker_helper = If you're running Gogs inside Docker, please read <a target="_blank" href="%s">Guidelines</a> carefully before you change anything in this page!
 requite_db_desc = Gogs requires MySQL, PostgreSQL, SQLite3 or TiDB.
 db_title = Database Settings
 db_type = Database Type

docker/README.md

@@ -48,6 +48,17 @@ Most of settings are obvious and easy to understand, but there are some settings
 
 Full documentation of settings can be found [here](http://gogs.io/docs/advanced/configuration_cheat_sheet.html).
 
+## Upgrade
+
+:exclamation::exclamation::exclamation:<span style="color: red">**Make sure you have volumed data to somewhere outside Docker container**</span>:exclamation::exclamation::exclamation:
+
+Steps to upgrade Gogs with Docker:
+
+- `docker pull gogs/gogs`
+- `docker stop gogs`
+- `docker rm gogs`
+- Finally, create container as the first time and don't forget to do same volume and port mapping.
+
 ## Troubleshooting
 
 If you see the following error:

templates/install.tmpl

@@ -8,6 +8,8 @@
 			<div class="ui attached segment">
         {{template "base/alert" .}}
 
+        <p>{{.i18n.Tr "install.docker_helper" "https://github.com/gogits/gogs/tree/master/docker" | Safe}}</p>
+
 			  <form class="ui form" action="{{AppSubUrl}}/install" method="post">
 			  	<!-- Dtabase Settings -->
 			  	<h4 class="ui dividing header">{{.i18n.Tr "install.db_title"}}</h4>