docs: fix typo in "Initializing a Selection" title (#5511)
docs: fix typo in "Initializing a Selection" title (#5511)


vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite