Fix typo in Overtone link

Add closing brace to Overtone link so link works correctly in Markdown.
Merge pull request #1 from ericnormand/patch-1

Fix typo in Overtone link
Update README.md
Update README.md
Update README.md
additional links
added links
added link
LightTable, Leiningen
add Clojure Babies links
Update README.md
Priority maps
Update README.md
added links
Update README.md

Add link to Grimoire Clojure Cheat Sheet
Merge pull request #2 from emlyn/patch-1

Update README.md
Update README.md
Update README.md
Update README.md
Update README.md