[document] Add vcpkg instruction step

[JackBoosY]

cpython is available as a port in vcpkg, a C++ library manager that simplifies installation for cpython and other project dependencies. Documenting the install process here will help users get started by providing a single set of commands to build cpython, ready to be included in their projects.

We also test whether our library ports build in various configurations (dynamic, static) on various platforms (OSX, Linux, Windows: x86, x64) to keep a wide coverage for users.

I'm a maintainer for vcpkg, and here is what the port script looks like. We try to keep the library maintained as close as possible to the original library. :)

[cpython-cla-bot]

All commit authors signed the Contributor License Agreement.

[JackBoosY]

Plz hide my mail address, and I've sign the CLA just now but I got: Internal Server Error.
Can you please re-check the CLA?

Thanks.

[zooba]

Could you add additional information about things like:

• where does the install go? How do I change it?
• how do I use it/run it?
• how do I remove/uninstall it?
• how do I provide compile-time options? Search paths?
• what dependencies do I need to already have installed?

It would also be good to have a link to somewhere that people can get help with vcpkg. It's not something we support directly, so assuming someone else does, we would want our users to know to go and ask them.