Design System - Update GradientScale story

[bradfordjanice]

What

Update the GradientScale story to follow the Design System pattern for stories.

Working with the existing stories create stories:

Standard - the common, default use of the GradientScale component in the CIVIC platform
Custom - add knobs for all props of the GradientScale component
Examples - examples of the component that show non-standard, but useful, configurations of the component.

Notes

Add GradientScale notes file. Notes describe each story and list the props/knobs that can be changed.

Why

Why does it need to be done?

GradientScale stories should follow the Civic design system pattern established in #508, #553, and #565. Please reference these files:

Bar Chart Component
-Bar Chart stories
-Bar Chart notes

Horizontal Bar Chart Component
-Horizontal Bar Chart stories
-Horizontal Bar Chart notes

When

When does this need to be done?
In the near future