Datepicker: Document key commands for OS X

[scottgonzalez]

Fixes gh-183

Not sure if this is the best way to document this.

[tjvantoll]

I don't like this because it's a bit ambiguous. For example, for “CTRL/COMMAND+HOME: Move to the current month”, I might assume that both CTRL + HOME, and COMMAND + HOME work on OS X, which they don't.

What if we were just added the OS X bindings in parenthesis?

• CTRL+HOME (COMMAND+HOME on OS X): Move to the current month

[scottgonzalez]

CTRL+HOME does work on OS X though. There may be specific key combos that overlap with default key commands on OS X, but datepicker doesn't actually implement different key bindings for different OSes.

[tjvantoll]

True. Well in that case it would be nice if there was something that logically separates the keys, because “CTRL/COMMAND+HOME” is hard to mentally parse.

• CTRL/COMMAND + HOME: lorem ipsum

<code> blocks could work, or a little CSS that makes the controls look like keys (which Kendo UI does: http://demos.telerik.com/kendo-ui/datepicker/keyboard-navigation).