Add the Minecraft Wiki information to server-properties.rst

Continuing my crusade to make things as easy as possible for those who need the docs translated (albeit with no heed to those poor souls who have to do the actual translating), I have added the information about each property found on Minecraft Wiki to this doc page (As a side note, tables are horrible to work on in Sphinx).

If you want to see the styling in practice, try https://livesphinx.herokuapp.com (you might have to zoom out a bit) (Thanks, Andrew).

I also have a few notes to the additions:

1. Is the info about strings on line 59 complete? I don't know if there's a cap on the length, other than the one mentioned in the MOTD-description.

2. Also MOTD-related: Do we want a doc page concerning colours and text formatting codes?

3. There are external links in generator-settings. While this is what I was trying to avoid by including this table, I would also argue that the information in this table is very relevant to those who check this page, whereas the specifics of world generation settings are not. Translations can simply state that more information for those who are interested is available in English on the Minecraft Wiki.