ci: remove Appveyor build

Windows binaries are also built in Travis CI now.

Author: igrr

README.md

@@ -54,6 +54,10 @@ Where:
 ```
 ## Build
 
+
+ [![Build status](http://img.shields.io/travis/igrr/mkspiffs.svg)](https://travis-ci.org/igrr/mkspiffs)
+
+
 You need gcc (≥4.8) or clang(≥600.0.57), and make. On Windows, use MinGW.
 
 Run:
@@ -100,13 +104,6 @@ SPIFFS configuration:
 ```
 
 
-### Build status
-
-Linux | Windows
-------|-------
- [![Linux build status](http://img.shields.io/travis/igrr/mkspiffs.svg)](https://travis-ci.org/igrr/mkspiffs) | [![Windows build status](http://img.shields.io/appveyor/ci/igrr/mkspiffs.svg)](https://ci.appveyor.com/project/igrr/mkspiffs)
-
-
 ## License
 
 MIT