Add a minimal, reproducible port example

[buracchi]

I'm trying to package a Github repository but I'm having an hard time.

In my humble opinion the packaging example is inadequate, take as an example the installing and using packages example, it contains probably all the information needed to use packages with vcpkg, you will actually need to read some of the documentation for adjust it to your needs (but nothing crazy) and you will probably be able set up your project in about 20 minutes.

Now, for the past days i've read several cmake and vcpkg documentation pages taking as reference other ports wich vastly differ from each other in an endless troubleshooting cycle, reaching the conclusion that package a repo shouldn't be this difficult.

I have come across several best practices and tips on several vcpkg documentation pages that I believe should be mentioned in the example under discussion. Instead of showing how to package an existing repository which doesn't use CMake I think it would be more usefull to show how to package a dummy repository consisting of a CMakeLists.txt file and a couple of source file showing some of the most interesting use cases, such as configuring namespace and optional features, display the usage message after the vcpkg install, create a target for find_package() and so on...