update links to v5

README.md

@@ -107,7 +107,7 @@ If a page request performance is more than a certain number of queries, a warnin
 
 ### System logs and messages
 
-The "Messages" tab will show you a list of anything that has been processed by [a SilverStripe logger](https://docs.silverstripe.org/en/4/developer_guides/debugging/error_handling/) during a page execution:
+The "Messages" tab will show you a list of anything that has been processed by [a SilverStripe logger](https://docs.silverstripe.org/en/5/developer_guides/debugging/error_handling/) during a page execution:
 
 ![System logs and messages](docs/_images/messages.png)
 
@@ -142,8 +142,8 @@ There is a variety of other useful information available via various tabs and in
 * **Parameters:** Displays all GET, POST and ROUTE parameters from the current request
 * **Config:** Displays a list of the current [SiteConfig](https://github.com/silverstripe/silverstripe-siteconfig) settings from the CMS
 * **Requirements:** Shows a list of all [`Requirements`](https://docs.silverstripe.org/en/developer_guides/templates/requirements/) calls made during a page's execution
-* **Middlewares:** Shows a list of all [`Middlewares`](https://docs.silverstripe.org/en/4/developer_guides/controllers/middlewares/) used for this request
-* **Mails:** Shows a list of all [emails](https://docs.silverstripe.org/en/4/developer_guides/email/) sent
+* **Middlewares:** Shows a list of all [`Middlewares`](https://docs.silverstripe.org/en/5/developer_guides/controllers/middlewares/) used for this request
+* **Mails:** Shows a list of all [emails](https://docs.silverstripe.org/en/5/developer_guides/email/) sent
 * **Headers:** Shows a list of all headers
 
 #### Indicators