Add examples and information on how to use custom growth functions

[stanleyrya]

Description

The growth function is called whenever the canvas is not large enough to fit all of the provided words (assuming growToFit is true).

It is currently a provided customization option but it doesn't have any examples or description. The purpose of this story is to fix that.

Acceptance Criteria

• The growth function customization option is either removed or has examples/a description