Update es-ES.coffee

Line #231, “Atajos de teclado” means “Keyboard Shortcuts” — let me know if this isn’t close enough to what is meant by “Key Bindings”: the reason that I chose this phrase is because I don’t know of an exact or approximate translation of “key bindings” into Spanish, but several other software platforms have used the phrase “atajos de teclado” to express this meaning.
Merge pull request #791 from Vindurrin/patch-1

Update es-ES.coffee