update readme with correct error message, add 1.12 and 1.11 to travis

.travis.yml

@@ -2,7 +2,9 @@ language: go
 sudo: false
 dist: trusty
 osx_image: xcode8.3
-go: 1.11.x
+go:
+  - 1.11.x
+  - 1.12.x
 
 os:
   - linux

README.md

@@ -3,6 +3,7 @@ cli
 
 [![Build Status](https://travis-ci.org/urfave/cli.svg?branch=master)](https://travis-ci.org/urfave/cli)
 [![Windows Build Status](https://ci.appveyor.com/api/projects/status/rtgk5xufi932pb2v?svg=true)](https://ci.appveyor.com/project/urfave/cli)
+
 [![GoDoc](https://godoc.org/github.com/urfave/cli?status.svg)](https://godoc.org/github.com/urfave/cli)
 [![codebeat](https://codebeat.co/badges/0a8f30aa-f975-404b-b878-5fab3ae1cc5f)](https://codebeat.co/projects/github-com-urfave-cli)
 [![Go Report Card](https://goreportcard.com/badge/urfave/cli)](https://goreportcard.com/report/urfave/cli)
@@ -888,7 +889,9 @@ Calling `App.Run` will not automatically call `os.Exit`, which means that by
 default the exit code will "fall through" to being `0`.  An explicit exit code
 may be set by returning a non-nil error that fulfills `cli.ExitCoder`, *or* a
 `cli.MultiError` that includes an error that fulfills `cli.ExitCoder`, e.g.:
-
+<!-- {
+  "error": "Ginger croutons are not in the soup"
+} -->
 ``` go
 package main