Doc tweaks for redirects. Closes #1501

Author: lonnieezell

system/Language/en/HTTP.php

@@ -31,7 +31,7 @@
    'emptySupportedNegotiations' => 'You must provide an array of supported values to all Negotiations.',
 
 	// RedirectResponse
-   'invalidRoute'               => '{0, string} is not a valid route.',
+   'invalidRoute'               => '{0, string} route cannot be found while reverse-routing.',
 
 	// DownloadResponse
    'cannotSetBinary'            => 'When setting filepath can not set binary.',

user_guide_src/source/general/common_functions.rst

@@ -244,6 +244,12 @@ Miscellaneous Functions
 		// Set a flash message
 		return redirect()->back()->with('foo', 'message');
 
+	When passing a URI into the function, it is treated as a reverse-route request, not a relative/full URI, treating
+    it the same as using redirect()->route()::
+
+        // Go to a named/reverse-routed URI
+		return redirect('named_route');
+
 .. php:function:: remove_invisible_characters($str[, $url_encoded = TRUE])
 
 	:param	string	$str: Input string