Update badges to point to lab

Author: mwcraig

.github/workflows/binder-badge.yml

@@ -21,7 +21,7 @@ jobs:
             issue_number: context.issue.number,
             owner: context.repo.owner,
             repo: context.repo.repo,
-            body: `[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/${PR_HEAD_USERREPO}/${PR_HEAD_REF}) :point_left: Launch a binder notebook on branch _${PR_HEAD_USERREPO}/${PR_HEAD_REF}_`
+            body: `[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/${PR_HEAD_USERREPO}/${PR_HEAD_REF}?urlpath=%2Flab) :point_left: Launch a binder notebook on branch _${PR_HEAD_USERREPO}/${PR_HEAD_REF}_`
           })
       env:
         PR_HEAD_REF: ${{ github.event.pull_request.head.ref }}

README.md

@@ -63,11 +63,11 @@ To update your copy of the tutorial materials, navigate in a terminal to folder
 
 ## Using binder
 
-[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/jupyter-widgets/tutorial/master?urlpath=%2Flab)
+Click the badge below to run the tutorial online:
 
-Many of the materials work without modification on mybinder.org without needing to install anything on your computer. However, this is *not* the recommended way to do the tutorial.
+[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/jupyter-widgets/tutorial/master?urlpath=%2Flab%2Ftree%2Fnotebooks)
 
-Go to [mybinder.org](https://mybinder.org/v2/gh/jupyter-widgets/tutorial/master) to run the tutorial online.
+Many of the materials work without modification on mybinder.org without needing to install anything on your computer. However, this is *not* the recommended way to do the tutorial.
 
 
 ## Any ipywidgets or custom widgets library question?