Fix URLs in documentation after repo transfer to KnightSoft

All the docs' urls pointed to SirCmpwn/KnightOS; the new, correct
location for the docs is KnightSoft/KnightOS.

Also, fixed a typo that was really annoying me in README.md.
Merge pull request #39 from thirtythreeforty/docs

Fix URLs in documentation after repo transfer to KnightSoft