Add /why command

[michael-kenzel]

Some of our current (and likely future) wiki articles do not fit the How to … scheme. In particular, we have:

• Why Should I Format My Code, and How Do I Do It?
• Why Is using namespace std Considered Bad Practice?
• What Is std::span and Why Should I Use It?
• What Is std::array And Why Should I Use It?
• Why Should I not #include <bits/stdc++.h>?
• What Is a VLA, and Why Is It "Bad"?

It is rather awkward to pull these up via the /howto command. We already have the general /wiki command. I would suggest to add /why and /what commands, and make it so that the /howto//why//what commands only list articles that fall into the How to …/Why …/What … scheme. This could be done by simply looking at the title, or by adding an HTML comment tag, or by reorganizing the wiki articles into howto/why/what subdirectories.

In addition to reduced awkwardness, this would also have the advantage of shortening the lists of suggestions, making the wiki a bit easier to navigate by being able to filter based on category, and maybe even making the wiki commands a bit less laggy…