Add Template build-configurations for CI systems from documentation

[nils-a]

Cake.Recipe has default/example build configurations for CI systems. It should be possible to add a default build configuration using this plugin.

Expected Behavior

• open command palette -> Cake.Recipe: Add default AppVeyor build configuration
• open command palette -> Cake.Recipe: Add default Azure DevOps build configuration
• open command palette -> Cake.Recipe: Add default GitHub Actions build configuration
• open command palette -> Cake.Recipe: Add default Travis CI build configuration

Current Behavior

Build configurations must be searched, then copy/pasted into a new file.

Possible Solution

Maybe it could be possible to move the current sample configurations out of the markdown and into independent files.
Those files could then be includeed back in the documentation and, additionally be the source of the operations above.

Context

Since I am lazy, I don't open the Cake.Recipe documentation to copy/paste the default build configurations, but rather I copy "some" configuration out of another project. This might lead to problems if the source of my copy process had some individualities that I forgot about.