docs: markup for code elements

README.md

@@ -119,7 +119,7 @@
 - [**State**](./docs/State.md)
   - [`createMemo`](./docs/createMemo.md) — factory of memoized hooks.
   - [`createReducer`](./docs/createReducer.md) — factory of reducer hooks with custom middleware.
-  - [`useDefault`](./docs/useDefault.md) — returns the default value when state is null or undefined.
+  - [`useDefault`](./docs/useDefault.md) — returns the default value when state is `null` or `undefined`.
   - [`useGetSet`](./docs/useGetSet.md) — returns state getter `get()` instead of raw state.
   - [`useGetSetState`](./docs/useGetSetState.md) — as if [`useGetSet`](./docs/useGetSet.md) and [`useSetState`](./docs/useSetState.md) had a baby.
   - [`usePrevious`](./docs/usePrevious.md) — returns the previous state or props.