message: docs: fix grammar of migration guide
diff: @@ -50,8 +50,8 @@ fix it.
  - Install the `framer-motion` package. We use this to manage animations and
  transitions within components.
  -- Remove the `emotion-theming` package. As at emotion v11, `emotion-theming` as
  - been removed and all it's functionality as been migrated to `@emotion/react`.
  +- Remove the `emotion-theming` package. As at emotion v11, `emotion-theming` has
  + been removed and all it's functionality has been migrated to `@emotion/react`.
  - Rename the `@emotion/core` package to `@emotion/react`. `@emotion/core` was
  recently changed to `@emotion/react` following the v11 release by the
  