When using H2, caution message shows at sign-in.

src/main/twirl/gitbucket/core/signin.scala.html

@@ -1,6 +1,7 @@
 @(userName: Option[Any] = None,
   password: Option[Any] = None,
   error: Option[Any] = None)(implicit context: gitbucket.core.controller.Context)
+@import gitbucket.core.util.DatabaseConfig
 @gitbucket.core.html.main("Sign in"){
   <div class="content-wrapper main-center">
     <div class="content body">
@@ -11,6 +12,12 @@
             @Html(information)
           </div>
         }
+        @if(DatabaseConfig.url.startsWith("jdbc:h2:")) {
+          <div class="alert alert-warning">
+            <button type="button" class="close" data-dismiss="alert">&times;</button>
+            H2 database should be used for evaluation purpose only.
+          </div>
+        }
         @gitbucket.core.helper.html.error(error)
         @gitbucket.core.html.signinform(context.settings, userName, password)
       </div>