Add tutorial for Getting Started with VS Code

[eXpl0it3r]

VS Code has gotten very popular over the past few years and we're seeing more questions on how to setup SFML with it, than we see questions regarding Code::Blocks or any other IDE. Add to the fact that VS Code work cross-platform, we're not just seeing Windows users, but also macOS and Linux users trying to make use of it.

I'd recommend two sections:

• How to use VS Code with the CMake extension
• How to use VS Code with simple tasks.json config

The CMake extension is in my opinion superior, especially when paired with the SFML CMake Template, but one down side is, that the run/debug button built into VS Code, don't actually trigger CMake.
Additionally, the tasks.json setup is the more "VSC way" of doing things, so it would be a bit ignorant, if we didn't cover it at all.

[eXpl0it3r]

With #167 we've added a link to the https://github.com/SFML/cmake-sfml-project and some additional words https://www.sfml-dev.org/tutorials/2.6/start-cmake.php

I wonder whether that's enough, or if we really need a tutorial for the tasks.json