Update phpdocs for better chaining

Following the PSR-5 Proposal, chained methods should use `return $this`.
New instances should use `return static`. This way, when classes are
extended, they refer to the correct class.

RedirectResponse.php

@@ -28,7 +28,7 @@ class RedirectResponse extends \Symfony\Component\HttpFoundation\RedirectRespons
 	 * @param  string  $key
 	 * @param  string  $value
 	 * @param  bool  $replace
-	 * @return \Illuminate\Http\RedirectResponse
+	 * @return $this
 	 */
 	public function header($key, $value, $replace = true)
 	{
@@ -62,7 +62,7 @@ public function with($key, $value = null)
 	 * Add a cookie to the response.
 	 *
 	 * @param  \Symfony\Component\HttpFoundation\Cookie  $cookie
-	 * @return \Illuminate\Http\RedirectResponse
+	 * @return $this
 	 */
 	public function withCookie(Cookie $cookie)
 	{
@@ -75,7 +75,7 @@ public function withCookie(Cookie $cookie)
 	 * Flash an array of input to the session.
 	 *
 	 * @param  array  $input
-	 * @return \Illuminate\Http\RedirectResponse
+	 * @return $this
 	 */
 	public function withInput(array $input = null)
 	{
@@ -89,8 +89,8 @@ public function withInput(array $input = null)
 	/**
 	 * Flash an array of input to the session.
 	 *
-	 * @param  dynamic  string
-	 * @return \Illuminate\Http\RedirectResponse
+	 * @param  mixed  string
+	 * @return $this
 	 */
 	public function onlyInput()
 	{
@@ -113,7 +113,7 @@ public function exceptInput()
 	 *
 	 * @param  \Illuminate\Support\Contracts\MessageProviderInterface|array  $provider
 	 * @param  string  $key
-	 * @return \Illuminate\Http\RedirectResponse
+	 * @return $this
 	 */
 	public function withErrors($provider, $key = 'default')
 	{

Request.php

@@ -22,7 +22,7 @@ class Request extends SymfonyRequest {
 	/**
 	 * Return the Request instance.
 	 *
-	 * @return \Illuminate\Http\Request
+	 * @return $this
 	 */
 	public function instance()
 	{

ResponseTrait.php

@@ -10,7 +10,7 @@ trait ResponseTrait {
 	 * @param  string  $key
 	 * @param  string  $value
 	 * @param  bool    $replace
-	 * @return \Illuminate\Http\Response
+	 * @return $this
 	 */
 	public function header($key, $value, $replace = true)
 	{
@@ -23,7 +23,7 @@ public function header($key, $value, $replace = true)
 	 * Add a cookie to the response.
 	 *
 	 * @param  \Symfony\Component\HttpFoundation\Cookie  $cookie
-	 * @return \Illuminate\Http\Response
+	 * @return $this
 	 */
 	public function withCookie(Cookie $cookie)
 	{