Focus and keyboard handling documentation

The Range Slider is now focusable, the elements that gets the focus when
the component is active are the slider's handles and progress tracker.

The full keyboard handling specifications are implemented.

Author: ndeshev

packages/main/src/RangeSlider.hbs

@@ -1,16 +1,14 @@
 {{>include "./SliderBase.hbs"}}
 
 {{#*inline "handles"}}
-	<div class="ui5-slider-handle ui5-slider-handle--start" style="{{styles.startHandle}}" @focusout={{_onfocusout}}
-	@focusin={{_onfocusin}}	tabindex="{{tabIndex}}">
+	<div class="ui5-slider-handle ui5-slider-handle--start" style="{{styles.startHandle}}" tabindex="{{tabIndex}}" @focusout="{{_onfocusout}}" @focusin="{{_onfocusin}}">
 		{{#if showTooltip}}
 			<div class="ui5-slider-tooltip ui5-slider-tooltip--start" style="{{styles.tooltip}}">
 				<span class="ui5-slider-tooltip-value">{{tooltipStartValue}}</span>
 			</div>
 		{{/if}}
 	</div>
-	<div class="ui5-slider-handle ui5-slider-handle--end" style="{{styles.endHandle}}" tabindex="{{tabIndex}}" @focusout={{_onfocusout}}
-	@focusin={{_onfocusin}}>
+	<div class="ui5-slider-handle ui5-slider-handle--end" style="{{styles.endHandle}}" tabindex="{{tabIndex}}" @focusout="{{_onfocusout}}" @focusin="{{_onfocusin}}">
 		{{#if showTooltip}}
 			<div class="ui5-slider-tooltip ui5-slider-tooltip--end" style="{{styles.tooltip}}">
 				<span class="ui5-slider-tooltip-value">{{tooltipEndValue}}</span>