Guide: explains the enum/match relationship

Closes #18169
This should mostly fix your grammar if you want it:
```
And that is how you handle sum types; thus we have a much simpler data
representation as well as data exploitation.  Pattern matching and enums really
are made for each other!
```

I think `exploitation` sounds weird and vague in this context and would probably change it to something more specific. Maybe `s/data exploitation/easy data extraction/`...but I'm sorta guessing as I'm not really sure what you're trying to say.

`sum types` was mentioned above in this diff but not explained. However, you don't get much out of mentioning it for those who don't understand `sum types`. For everyone who doesn't, something like:
```
so you see that `enum` and `match` together allow very compact combination branching and destructuring
```
 would be more enlightening.