docs: replace link to link to page with link to page

* Previously documentation link pointed to
  https://github.com/tektoncd/pipeline/blob/main/docs/tutorial.md
  which then pointed you onwards to
  https://tekton.dev/docs/getting-started/
* Simplify this by directly pointing user to end destination

docs/README.md

@@ -54,7 +54,7 @@ Tekton Pipelines defines the following entities:
 
 ## Getting started
 
-To get started, complete the [Tekton Pipelines Tutorial](https://github.com/tektoncd/pipeline/blob/main/docs/tutorial.md) and go through our
+To get started, complete the [Tekton Pipelines Tutorial](https://tekton.dev/docs/getting-started) and go through our
 [examples](https://github.com/tektoncd/pipeline/tree/main/examples).
 
 ## Understanding Tekton Pipelines