added redirect documentation

Author: adrum

v1/the-basics/redirects.mdx

@@ -63,7 +63,9 @@ public class UsersController : Controller
         });
         _context.SaveChanges();
 
-        return RedirectToAction("Index");
+        return Inertia.Back();
+        //
+        // return RedirectToAction(nameof(Index));
     }
 }
 ```
@@ -76,6 +78,12 @@ When redirecting after a `PUT`, `PATCH`, or `DELETE` request, you must use a `30
 
 If you're using one of our official server-side adapters, all redirects will automatically be converted to `303` redirects.
 
+When using `InertiaCore`, redirects created via `Inertia.Back()` are automatically converted to `303` responses. You may optionally pass a fallback URL (used when the `Referer` header is unavailable) and a custom status code:
+
+```csharp
+return Inertia.Back(fallbackUrl, statusCode);
+```
+
 ## External Redirects
 
 Sometimes it's necessary to redirect to an external website, or even another non-Inertia endpoint in your app while handling an Inertia request. This can be accomplished using a server-side initiated `window.location` visit via the `Inertia::location()` method.

v2/the-basics/redirects.mdx

@@ -66,7 +66,9 @@ public class UsersController : Controller
         _context.Users.Add(new User { Name = request.Name, Email = request.Email });
         await _context.SaveChangesAsync();
 
-        return RedirectToAction("Index");
+        return Inertia.Back();
+        //
+        // return RedirectToAction(nameof(Index));
     }
 }
 ```
@@ -79,6 +81,12 @@ When redirecting after a `PUT`, `PATCH`, or `DELETE` request, you must use a `30
 
 If you're using one of our official server-side adapters, all redirects will automatically be converted to `303` redirects.
 
+When using `InertiaCore`, redirects created via `Inertia.Back()` are automatically converted to `303` responses. You may optionally pass a fallback URL (used when the `Referer` header is unavailable) and a custom status code:
+
+```csharp
+return Inertia.Back(fallbackUrl, statusCode);
+```
+
 ## External Redirects
 
 Sometimes it's necessary to redirect to an external website, or even another non-Inertia endpoint in your app while handling an Inertia request. This can be accomplished using a server-side initiated `window.location` visit via the `Inertia::location()` method.

v3/the-basics/redirects.mdx

@@ -62,7 +62,9 @@ public class UsersController : Controller
         _context.Users.Add(new User { Name = request.Name, Email = request.Email });
         await _context.SaveChangesAsync();
 
-        return RedirectToAction("Index");
+        return Inertia.Back();
+        //
+        // return RedirectToAction(nameof(Index));
     }
 }
 ```
@@ -75,6 +77,12 @@ When redirecting after a `PUT`, `PATCH`, or `DELETE` request, you must use a `30
 
 If you're using one of our official server-side adapters, all redirects will automatically be converted to `303` redirects.
 
+When using `InertiaCore`, redirects created via `Inertia.Back()` are automatically converted to `303` responses. You may optionally pass a fallback URL (used when the `Referer` header is unavailable) and a custom status code:
+
+```csharp
+return Inertia.Back(fallbackUrl, statusCode);
+```
+
 ## Preserving Fragments
 
 Sometimes a user may visit a URL with a fragment, such as `/article/old-slug#section`, and the server needs to redirect to a different URL. The fragment from the original request is normally lost during the redirect.