[style] remove .md-content min-height override

[the-overdriven]

Before (current):

What's the point of making short pages so long?

I believe it's an old override that doesn't take header and footer height into account anymore, so that the whole page min-height isn't 100vh (as expected), but rather becomes: 100vh + header height + footer height, which adds an unnecessary scroll.

After (this MR):

[kamilkrzyskow]

iirc it was made to remove/avoid double scrollbars.
Please check on standard 1080p the Zengin section where the nav is a lot longer and see the website (body) having no scrollbar and yet the nav having one. UX is better with one body scrollbar imo, but I don't remember discussion about it on Discord, perhaps I just decided so on a whim 🤔

EDIT:
OK, like you said it's an older override from the time when the Zengin index would expand the whole nav tree and this would result in a very short body without a scrollbar and very narrow nav section with a long nav scrollbar.

Currently it doesn't auto-expand on the index, and the separate nav scrollbar is not so bad in a deeper page, since the user already (probably) navigated to the site they want, so no need to scroll over the whole nav to find something else.

[kamilkrzyskow]

Therefore after the edit above LGTM, but I'll ask for a review from Emu.

[kamilkrzyskow]

Auronen gave the green light on Discord, so I guess that's enough ✌️