Make index.md generated from canonical GopherJS README.

README.md

@@ -1,5 +1,11 @@
 # GopherJS.org
 
+## Generating
+
+```bash
+go generate github.com/gopherjs/gopherjs.github.io/...
+```
+
 ## Todo
 
 * Tweak look and feel, logo, etc.

doc.go

@@ -0,0 +1,6 @@
+// Package gopherjswebsite is the www.gopherjs.org website source.
+//
+// It should be updated with `go generate github.com/gopherjs/gopherjs.github.io/...`.
+package gopherjswebsite
+
+//go:generate go run generate.go

generate.go

@@ -0,0 +1,68 @@
+// +build generate
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"text/template"
+)
+
+func t(text string) *template.Template {
+	return template.Must(template.New("").Parse(text))
+}
+
+// Filename -> Template.
+var templates = map[string]*template.Template{
+
+	"index.md": t(`---
+# generated by generate.go; DO NOT EDIT
+layout: index
+title: Home
+permalink: /
+---
+
+{{.HTTPGet "https://raw.githubusercontent.com/gopherjs/gopherjs/master/README.md"}}`),
+}
+
+type data struct{}
+
+// HTTPGet fetches the contents at the given url.
+func (data) HTTPGet(url string) (string, error) {
+	resp, err := http.Get(url)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return "", err
+	}
+	return string(body), nil
+}
+
+func gen() error {
+	for filename, t := range templates {
+		var buf bytes.Buffer
+		err := t.Execute(&buf, data{})
+		if err != nil {
+			return err
+		}
+		fmt.Println("writing", filename)
+		err = ioutil.WriteFile(filename, buf.Bytes(), 0644)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func main() {
+	err := gen()
+	if err != nil {
+		log.Fatalln(err)
+	}
+}

index.md

@@ -1,4 +1,5 @@
 ---
+# generated by generate.go; DO NOT EDIT
 layout: index
 title: Home
 permalink: /
@@ -7,6 +8,8 @@ permalink: /
 GopherJS - A compiler from Go to JavaScript
 -------------------------------------------
 
+[![Circle CI](https://circleci.com/gh/gopherjs/gopherjs.svg?style=svg)](https://circleci.com/gh/gopherjs/gopherjs)
+
 GopherJS compiles Go code ([golang.org](http://golang.org/)) to pure JavaScript code. Its main purpose is to give you the opportunity to write front-end code in Go which will still run in all browsers. Give GopherJS a try on the [GopherJS Playground](http://gopherjs.github.io/playground/).
 
 ### What is supported?
@@ -31,6 +34,7 @@ Now you can use  `gopherjs build [files]` or `gopherjs install [package]` which
 - Use `float64` instead of `float32`.
 
 ### Community
+- [#gopherjs Channel on Gophers Slack](https://gophers.slack.com/messages/gopherjs/) (invites to Gophers Slack are available [here](http://blog.gopheracademy.com/gophers-slack-community/#how-can-i-be-invited-to-join:2facdc921b2310f18cb851c36fa92369))
 - [Google Group](https://groups.google.com/d/forum/gopherjs)
 - [Bindings to JavaScript APIs and libraries](https://github.com/gopherjs/gopherjs/wiki/bindings)
 - [GopherJS on Twitter](https://twitter.com/GopherJS)