chore(docs): rebuild table from all-tokens json

[evwilkin]

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Closes #68

This PR implements new tokens tables which:

• display tokens based on their layer (semantic, base, palette, charts)
• displays default & dark theme values for all tokens
• displays token chains for both default & dark theme values
• pulls in new token descriptions and displays them (currently only applicable to semantic tokens)

README has been updated to explain commands to execute this code, but in summary the data needed for the table is pulled when yarn build or yarn build:scss is run (they trigger the same code), as two new json files containing all the token data displayed in the table are created by Style Dictionary in the same process as the scss files creation.

[evwilkin]

Thanks @srambach for the feedback - I'll take a look at addressing your comments, not quite sure what I did to get those double checkmarks so thanks for catching that 🤔