Add badges for CI services.

Travis-CI or appveyor or similar. They appear in the top-level README and
provide a link or similar.

See:

* https://en.wikipedia.org/wiki/Continuous_integration .

"Badges? We don't need no stinkin' badges!"

https://en.wikipedia.org/wiki/Stinking_badges

README.md

@@ -1,6 +1,8 @@
 # fortune-mod Maintenance Version and Ongoing Development
 
-[![Build Status](https://travis-ci.org/shlomif/fortune-mod.svg?branch=master)](https://travis-ci.org/shlomif/fortune-mod)
+[![Travis-CI Build Status](https://travis-ci.org/shlomif/fortune-mod.svg?branch=master)](https://travis-ci.org/shlomif/fortune-mod)
+
+[![AppVeyor Build status](https://ci.appveyor.com/api/projects/status/0pbvqd1xa7777aoo/branch/master?svg=true)](https://ci.appveyor.com/project/shlomif/fortune-mod/branch/master)
 
 This GitHub repository maintains the sources for fortune-mod, a
 version of