Remove appveyor badge (for now)

README.md

@@ -1,6 +1,6 @@
 <img src="DOC/logo-text.png" height=100></img>
 
-[![Circle CI](https://circleci.com/gh/rqlite/rqlite/tree/master.svg?style=svg)](https://circleci.com/gh/rqlite/rqlite/tree/master)  [![appveyor](https://ci.appveyor.com/api/projects/status/github/rqlite/rqlite?branch=master&svg=true)](https://ci.appveyor.com/project/otoolep/rqlite) [![Go Report Card](https://goreportcard.com/badge/github.com/rqlite/rqlite)](https://goreportcard.com/report/github.com/rqlite/rqlite) [![Release](https://img.shields.io/github/release/rqlite/rqlite.svg)](https://github.com/rqlite/rqlite/releases) [![Docker](https://img.shields.io/docker/pulls/rqlite/rqlite?style=plastic)](https://hub.docker.com/r/rqlite/rqlite/) [![Google Group](https://img.shields.io/badge/Google%20Group--blue.svg)](https://groups.google.com/group/rqlite) [![Slack](https://img.shields.io/badge/Slack--purple.svg)](https://www.philipotoole.com/join-rqlite-slack)
+[![Circle CI](https://circleci.com/gh/rqlite/rqlite/tree/master.svg?style=svg)](https://circleci.com/gh/rqlite/rqlite/tree/master) [![Go Report Card](https://goreportcard.com/badge/github.com/rqlite/rqlite)](https://goreportcard.com/report/github.com/rqlite/rqlite) [![Release](https://img.shields.io/github/release/rqlite/rqlite.svg)](https://github.com/rqlite/rqlite/releases) [![Docker](https://img.shields.io/docker/pulls/rqlite/rqlite?style=plastic)](https://hub.docker.com/r/rqlite/rqlite/) [![Google Group](https://img.shields.io/badge/Google%20Group--blue.svg)](https://groups.google.com/group/rqlite) [![Slack](https://img.shields.io/badge/Slack--purple.svg)](https://www.philipotoole.com/join-rqlite-slack)
 
 *rqlite* is an easy-to-use, lightweight, distributed relational database, which uses [SQLite](https://www.sqlite.org/) as its storage engine.