Fix broken protocol in link to Firefox DevTools addon (reduxjs#4082)

Author: T1mL3arn

docs/tutorials/fundamentals/part-4-store.md

@@ -543,7 +543,7 @@ Finally, there's one more very important thing to cover with configuring the sto
 
 **Redux was specifically designed to make it easier to understand when, where, why, and how your state has changed over time**. As part of that, Redux was built to enable the use of the **Redux DevTools** - an addon that shows you a history of what actions were dispatched, what those actions contained, and how the state changed after each dispatched action.
 
-The Redux DevTools UI is available as a browser extension for [Chrome](https://chrome.google.com/webstore/detail/redux-devtools/lmhkpmbekcpmknklioeibfkpmmfibljd?hl=en) and [Firefox](ttps://addons.mozilla.org/en-US/firefox/addon/reduxdevtools/). If you haven't already added that to your browser, go ahead and do that now.
+The Redux DevTools UI is available as a browser extension for [Chrome](https://chrome.google.com/webstore/detail/redux-devtools/lmhkpmbekcpmknklioeibfkpmmfibljd?hl=en) and [Firefox](https://addons.mozilla.org/en-US/firefox/addon/reduxdevtools/). If you haven't already added that to your browser, go ahead and do that now.
 
 Once that's installed, open up the browser's DevTools window. You should now see a new "Redux" tab there. It doesn't do anything, yet - we've got to set it up to talk to a Redux store first.