Update to Myth Compendium 1 for Mythic Bastionland

A small update!

Mostly fixing spelling, wording and also polishing everything a little bit to make it look more presentable.

- Cut down the file size by a large chunk
- Added a pretty border with some help from my wonderful partner
- Renamed two Myths to better fit their theme ("Crater" to "Chasm" and "Snow" to "Cold")
- Slightly adjusted some of the d6 tables, mostly to make items more flavorful
- Slightly adjusted phrasing here and there, mostly just to  make things clearer
- Adjusted wording to better reflect that of the original core book
- Adjusted capitalization to better reflect the style in the original core book
- Fixed some minor spelling mistakes
- Adjusted image layout, I hope it looks a little nicer like this