Art request - Competitor pricing graph

[joethreepwood]

Outline

It's just like #8300 (comment) but with some extra lines, to show competitors.

Sheet: https://docs.google.com/spreadsheets/d/1wMvKa_42uiplfds0a3keFZLJtcc8dslWJyv6iilLs4A/edit#gid=978028988

The yellow line is Mixpanel's pricing. Amplitude bills differently, and Heap's pricing is opaque. Even Mixpanel only gives pricing to 20M events.

In the legend, please list Mixpanel with a subtitle: Growth plan, no add-ons.

[joethreepwood]

Given that we use yellow as a line on the other charts, we should probably make Mixpanel's line a non-yellow colour too

[lottiecoxon]