chore(docs): adds docs for useCurrentUser hook (#4919)

* chore(docs): adds docs for useCurrentUser hook

* docs(core): update docs for useCurrentUser hook

Co-authored-by: Espen Hovlandsdal <espen@hovlandsdal.com>

---------

Co-authored-by: Espen Hovlandsdal <espen@hovlandsdal.com>

packages/sanity/src/core/store/user/hooks.ts

@@ -22,7 +22,22 @@ export function useUser(userId: string): LoadingTuple<User | null | undefined> {
   return useUserViaUserStore(useMemo(() => [userStore, userId], [userId, userStore]))
 }
 
-/** @internal */
+/**
+ * Retrieves information about the currently authenticated user.
+ *
+ * @returns The current user or null if not available.
+ *
+ * @public
+ *
+ * @example
+ * ```ts
+ * const currentUser = useCurrentUser()
+ *
+ * if (currentUser) {
+ *  console.log('Logged in as', currentUser.name)
+ * }
+ * ```
+ */
 export function useCurrentUser(): CurrentUser | null {
   const {currentUser} = useSource()
   return currentUser