Update README & CONTRIBUTING

Fix broken links for Dev Chat that point to broken gitter.im room.
Remove lines about `mage vendor` target that is no longer available.
Remove broken table of contents links for headings in CONTRIBUTING.md
Fix typo

1 files changed, 3 insertions, 3 deletions

diff --git a/README.md b/README.md
index d97011da0..0f0560196 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@ A Fast and Flexible Static Site Generator built with love by [bep](https://githu
 
 [Website](https://gohugo.io) |
 [Forum](https://discourse.gohugo.io) |
-[Developer Chat (no support)](https://gitter.im/gohugoio/hugo) |
+[Developer Chat (no support)](https://gitter.im/spf13/hugo) |
 [Documentation](https://gohugo.io/overview/introduction/) |
 [Installation Guide](https://gohugo.io/overview/installing/) |
 [Contribution Guide](CONTRIBUTING.md) |
@@ -13,7 +13,7 @@ A Fast and Flexible Static Site Generator built with love by [bep](https://githu
 [![GoDoc](https://godoc.org/github.com/gohugoio/hugo?status.svg)](https://godoc.org/github.com/gohugoio/hugo)
 [![Linux and macOS Build Status](https://api.travis-ci.org/gohugoio/hugo.svg?branch=master&label=Linux+and+macOS+build "Linux and macOS Build Status")](https://travis-ci.org/gohugoio/hugo)
 [![Windows Build Status](https://ci.appveyor.com/api/projects/status/a5mr220vsd091kua?svg=true&label=Windows+build "Windows Build Status")](https://ci.appveyor.com/project/bep/hugo/branch/master)
-[![Dev chat at https://gitter.im/gohugoio/hugo](https://img.shields.io/badge/gitter-developer_chat-46bc99.svg)](https://gitter.im/spf13/hugo?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Dev chat at https://gitter.im/spf13/hugo](https://img.shields.io/badge/gitter-developer_chat-46bc99.svg)](https://gitter.im/spf13/hugo?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 [![Go Report Card](https://goreportcard.com/badge/github.com/gohugoio/hugo)](https://goreportcard.com/report/github.com/gohugoio/hugo)
 
 ## Overview
@@ -61,7 +61,7 @@ Use the [installation instructions in the Hugo documentation](https://gohugo.io/
 
 #### Fetch from GitHub
 
-Since Hugo 0.48, Hugo uses the Go Modules support built into Go 1.11 to build. The easiest is is to clone Hugo in a directory outside of `GOPATH`, as in the following example:
+Since Hugo 0.48, Hugo uses the Go Modules support built into Go 1.11 to build. The easiest is to clone Hugo in a directory outside of `GOPATH`, as in the following example:
 
 ```bash
 mkdir $HOME/src