Format README markdown

[shaneshame]

A fairly trivial commit to:

• Enable HTML headers and DOM anchor queries in urls, e.g. https://github.com/Steell/Ultimate-Mapchooser#end-of-map-vote. (Example on my branch to go to the End of Map Vote header.)

• Add code styling to file names:

  Similar to the functionality built into randomcycle.smx, but random maps are selected at the END of the map, rather than the beginning, and maps are checked for exclusion before being selected (see Map Exclusion).