fixed broken links to contributing.md

also removed the "Why Odin?" link at the bottom as it is invalid and I don't see that markdown file currently in the curriculum repo
fixed broken links to contributing.md

commented out the "Why Odin" section as well.
Update getting_started.md

Commented out the "Why Odin" section as per hgducharme's request.
Merge pull request #775 from vdubmastertech/patch-2

fixed broken links to contributing.md