Update transform.md
Update transform.md

Curly braces seems not working. So I changed the link to use a longer version of the section name.
vega/vega-lite,vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite