Update docs to emphasize selector can be a string or a DOM node
clarify wording
Merge branch 'pr/644'

Conflicts:
	src/bar-chart.js
	src/base-mixin.js
	src/box-plot.js
	src/bubble-chart.js
	src/bubble-overlay.js
	src/composite-chart.js
	src/data-count.js
	src/data-grid.js
	src/data-table.js
	src/geo-choropleth-chart.js
	src/heatmap.js
	src/line-chart.js
	src/number-display.js
	src/pie-chart.js
	src/row-chart.js
	src/scatter-plot.js
	src/series-chart.js
	web/docs/api-latest.md