docs(api): add docs for useRouter composable (#4949)

Co-authored-by: Daniel Roe <daniel@roe.dev>

docs/content/3.api/1.composables/use-router.md

@@ -1,7 +1,62 @@
 # `useRouter`
 
+The `useRouter` composable returns the router instance and must be called in a `setup` function, plugin, or route middleware. (Within the template of a Vue component, you can access the router using `$router` instead.)
+
+If you have a `pages/` folder, `useRouter` is identical in behavior to the one provided by `vue-router`. Feel free to read the router documentation for more information on what each method does.
+
+::ReadMore{link="https://router.vuejs.org/api/#currentroute"}
+::
+
+## Basic manipulation
+
+- **addRoute:** Add a new route to the router instance. `parentName` can be provided to add new route as the child of an existing route.
+- **removeRoute:** Remove an existing route by its name.
+- **getRoutes:** Get a full list of all the route records.
+- **hasRoute:** Checks if a route with a given name exists
+
+## Based on history API
+
+- **back:** Go back in history if possible, same as `router.go(-1)`.
+- **forward:** Go forward in history if possible, same as `router.go(1)`.
+- **go:** Move forward or backward through the history without the hierarchical restrictions enforced in `router.back()` and `router.forward()`.
+- **push:** Programmatically navigate to a new URL by pushing an entry in the history stack. **It is recommended to use [`navigateTo`](http://v3.nuxtjs.org/api/utils/navigate-to#navigateto) instead.**
+- **replace:** Programmatically navigate to a new URL by replacing the current entry in the routes history stack. **It is recommended to use [`navigateTo`](http://v3.nuxtjs.org/api/utils/navigate-to#navigateto) instead.**
+
+> TIP: `router.addRoute()` adds route details into an array of routes and it is useful while building Nuxt plugins while `router.push()` on the other hand, triggers a new navigation immediately and it is useful in Nuxt Page components, Vue components and composable.
+
+```js [js]
+const router = useRouter();
+router.back();
+router.forward();
+router.go();
+router.push({ path: "/home" });
+router.replace({ hash: "#bio" });
+````
+
+::ReadMore{link="https://developer.mozilla.org/en-US/docs/Web/API/History"}
+::
+
+## Navigation guards
+
+`useRouter` composable provides `afterEach`, `beforeEach` and `beforeResolve` helper methods that acts as nagivation guards.
+
+However, Nuxt has a concept of **route middleware** that simplifies the implementation of navigation guards and provides a better developer experience.
+
+::ReadMore{link="/guide/directory-structure/middleware"}
+::
+
+## Promise and error handling
+
+- **isReady:** Returns a Promise that resolves when the router has completed the initial navigation.
+- **onError:** Adds an error handler that is called every time a non caught error happens during navigation.
+- **resolve:** Returns the normalized version of a route location. Also includes an `href` property that includes any existing base.
+
+::ReadMore{link="https://router.vuejs.org/api/#router-methods"}
+::
+
+## Universal router instance
+
+If you do not have a `pages/` folder, then `useRouter` will return a universal router instance with similar helper methods, but be aware that not all features may be supported or behave in exactly the same way as with `vue-router`.
+
 ::ReadMore{link="/guide/features/routing"}
 ::
-
-::NeedContribution
-::