spacing story

[claireclark1]

Problem

Define spacing

closes #4

Solution

• By setting spacing, we're defining pixel values that can be used across all types of styling, such as gap, padding, width, etc.
• Create a storybook to display.
• Added the "f" prefix to the values to indicate that it's frequency's style-guide values and to not override the defaults, potentially breaking a lot of formatting.

Steps to Verify:

1. Check that spacing looks good on the storybook

Screenshots (optional):