AppVeyor: prevent unnecessary builds (#2888)

* prevent unnecessarybuilds

* readd qt5 string

sadly this is needed as of now:
ff6b0f86ec/cockatrice/src/releasechannel.cpp (L59-L68)

* wrap asterisks

* fixed with validator

https://ci.appveyor.com/tools/validate-yaml

* complete link

* add helpful links

this should not trigger a appveyor build

* add space in readme

this should not trigger a appveyor build

* highlight c++ types

this should not trigger a appveyor build

* remove empty line

this should not trigger a appveyor build

* declutter dockerignore

this should not trigger a appveyor build

README.md

@@ -23,7 +23,7 @@ We offer downloads for all full releases (recommended) and the latest developmen
 
 - Latest full release (**recommended**): [![Download from GitHub Releases](https://img.shields.io/github/release/cockatrice/cockatrice.svg)](https://github.com/cockatrice/cockatrice/releases/latest) [![Download Count on Latest Release](https://img.shields.io/github/downloads/cockatrice/cockatrice/latest/total.svg)](https://tooomm.github.io/github-release-stats/?username=Cockatrice&repository=Cockatrice)<br>
 
-- Latest development version: [![Download from GitHub Pre-Releases](https://img.shields.io/github/release/cockatrice/cockatrice/all.svg)](https://github.com/cockatrice/cockatrice/releases)
+- Latest development version: [![Download from GitHub Pre-Releases](https://img.shields.io/github/release/cockatrice/cockatrice/all.svg)](https://github.com/cockatrice/cockatrice/releases) 
    - Development builds may not be stable and/or contain several bugs.
    - If you'd like to be a Cockatrice Beta Tester, use this version.
    - More information can be [found here](https://github.com/Cockatrice/Cockatrice/wiki/Release-Channels)