v0.5.2: Missing Button State; Fix an Import, Button Size, Docs

Fixed

• feat(FP-1596): design button "--is-active" type (#24)
• fix(FP-1596): missing import for truncate extend
• fix(fp-1678): small button a bit more vert pad (#30)

Changed

• docs(README): module usage: fix typo, drop old opt
• docs(styles): readme, related repos & old callout