docs: include link to TanStack Store docs within description of store property (#517)

The TanStack Store instance has some useful methods of its own. It may be helpful to provide a link to its docs from here.

Author: alexkatz

docs/reference/formApi.md

@@ -98,7 +98,7 @@ A class representing the Form API. It handles the logic and interactions with th
 - ```tsx
   store: Store<FormState<TFormData>>
   ```
-  - An internal mechanism that keeps track of the form's state.
+  - A [TanStack Store instance](https://tanstack.com/store/latest/docs/reference/Store) that keeps track of the form's state.
 - ```tsx
   state: FormState<TFormData>
   ```