corrects tutorial url for the flux blog (#4934)

The existing URL leads to a 404 page hence this PR updates it to the Github page containing the content for the tutorial.

content/blog/2014-05-06-flux.md

@@ -13,4 +13,4 @@ In Flux, the Dispatcher is a singleton that directs the flow of data and ensures
 
 When a user interacts with a React view, the view sends an action (usually represented as a JavaScript object with some fields) through the dispatcher, which notifies the various stores that hold the application's data and business logic. When the stores change state, they notify the views that something has updated. This works especially well with React's declarative model, which allows the stores to send updates without specifying how to transition views between states.
 
-Flux is more of a pattern than a formal framework, so you can start using Flux immediately without a lot of new code. An [example of this architecture](https://github.com/facebook/flux/tree/master/examples/flux-todomvc) is available, along with more [detailed documentation](https://facebook.github.io/flux/docs/overview.html) and a [tutorial](https://facebook.github.io/flux/docs/todo-list.html). Look for more examples to come in the future.
+Flux is more of a pattern than a formal framework, so you can start using Flux immediately without a lot of new code. An [example of this architecture](https://github.com/facebook/flux/tree/master/examples/flux-todomvc) is available, along with more [detailed documentation](https://facebook.github.io/flux/docs/overview.html) and a [tutorial](https://github.com/facebook/flux/tree/main/examples/flux-todomvc). Look for more examples to come in the future.