insights: Language use – note that if you want them over time or over all repos you need a different type

Created by: Joelkw

Sometimes users go to the pie chart and want to instead see languages over time, and then are not able to figure out how to do that.

The only supported way to do this right now is to make a line chart track anything insight with a query like select:file lang:TypeScript.

We should add a note to the pie chart creation UI like "want languages over time, or to track languages across all repos? Use a 'track anything' insight to count files by language" that takes you to a track-anything insight with the template for language tracking (the above query) already filled out.