[appveyor] Skip AppVeyor builds for boring files
[appveyor] Skip AppVeyor builds for boring files

This list is not exhaustive (e.g., CONTRIBUTING.md is not included). To
keep it maintainable, it only contains high-churn files that don't
affect the build.

* CHANGELOG.md doesn't affect the build but get changes almost daily.
* Travis CI-specific files don't affect the Windows builds.
sapek/bond,tstein/bond,jdubrule/bond,jdubrule/bond,chwarr/bond,chwarr/bond,Microsoft/bond,tstein/bond,Microsoft/bond,chwarr/bond,sapek/bond,tstein/bond,chwarr/bond,gencer/bond,sapek/bond,sapek/bond,gencer/bond,sapek/bond,Microsoft/bond,gencer/bond,gencer/bond,jdubrule/bond,jdubrule/bond,gencer/bond,Microsoft/bond,Microsoft/bond,jdubrule/bond,tstein/bond,Microsoft/bond,tstein/bond,sapek/bond,jdubrule/bond,chwarr/bond,tstein/bond,chwarr/bond