Update config.json

[depial]

The practice exercises were not ordered by difficulty. This is addressed here.

No particular order has been followed outside of the difficulty level (and keeping Hello World! first).

I didn't look too carefully at which exercises received what rating, but it might be good to have a second look through the difficulty 1 group since that is the default assignment given by configlet, and so it's possible to create a more difficult exercise and miss changing that bit (e.g. is roman-numerals a 1?)

[depial]

The Configlet check got cancelled because:

The job was not acquired by Runner of type hosted even after multiple attempts

I've never seen that before...

[colinleach]

I've never seen that before...

Nor have I! I have no idea what it means, but my guess is that GitHub are having a bad day. Let's try again in a few hours and hope the problem magically disappears.

it might be good to have a second look through the difficulty 1 group

I'll add it to the TODO list. I suspect it's been a few years since this was last reviewed.

[colinleach]

I changed Roman Numerals to difficulty 2, same as Python. I looked at the example.R and it's not too bad. In a shock development, it looks like I even wrote approaches!

Meanwhile, this triggered a CI rerun and it now seems to work.