Add ReadTheDocs preview workflow (#59)

Author: jtpio

.github/workflows/rtd-preview.yml

@@ -0,0 +1,24 @@
+name: RTD Preview
+on:
+  pull_request_target:
+    types: [opened]
+
+permissions:
+  pull-requests: write
+
+jobs:
+  binder:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Comment on the PR with the RTD preview
+        uses: actions/github-script@v6
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            var PR_NUMBER = context.issue.number
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `[![lite-badge](https://jupyterlite.rtfd.io/en/latest/_static/badge.svg)](https://jupyterlab-filesystem-access--${PR_NUMBER}.org.readthedocs.build/en/${PR_NUMBER}/lite) :point_left: Try it on ReadTheDocs`
+            })