Responsive grid

### Is your feature request related to a problem? Please describe.
I get frustrated that:
- Each commit to add a new contributor is a rather large commit because of the way the HTML is set up ([example](https://github.com/alan-turing-institute/the-turing-way/pull/2764/files#diff-b335630551682c19a781afebcf4d07bf978fb1f8ac04c6bf87428ed5106870f5))
- The grid on the readme is not responsive so when it is viewed on a small screen the right-most columns get cut off

### Describe the solution you'd like
A system whereby the grid was made responsive such that when a new user was added, it didn't change the whole grid (and also so that it looks nice).

### Describe alternatives you've considered
We could [turn off alphabetic ordering for our grid](https://github.com/alan-turing-institute/the-turing-way/pull/2681), and that would be a partial solution.

### Additional context
**I've mocked up a hacky idea [here](https://github.com/da5nsy/css-in-readme-like-wat).**
I don't really know HTML/CSS, and so this is probably as far as I can push this, but I think there might be something there that others might be able to use for inspiration. It's based on a combo of [this](https://mastery.games/post/tile-layouts/) and [this](https://github.com/sindresorhus/css-in-readme-like-wat).
_(For some reason, the image links aren't working 🤷 )_