Add a Circle CI job to show a preview of the docs on PRs

Fixes sympy#23460.

.circleci/config.yml

@@ -0,0 +1,32 @@
+version: 2
+
+# Aliases to reuse
+_defaults: &defaults
+  docker:
+    # CircleCI maintains a library of pre-built images
+    # documented at https://circleci.com/docs/2.0/circleci-images/
+    - image: cimg/python:3.10.2
+  working_directory: ~/repo
+
+jobs:
+  build_page:
+    <<: *defaults
+    steps:
+      - checkout
+      - attach_workspace:
+          at: ~/
+      - run:
+          name: build docs
+          no_output_timeout: 25m
+          command: |
+            cd doc
+            pip install -r requirements.txt
+            make html
+      - store_artifacts:
+          path: _build/html
+
+workflows:
+  version: 2
+  default:
+    jobs:
+      - build_page

.github/workflows/docs-preview.yml

@@ -0,0 +1,19 @@
+on: [status]
+jobs:
+  circleci_artifacts_redirector_job:
+    # Don't run Action on forks, and allow skipping CI
+    if: "github.repository == 'sympy/sympy'"
+    runs-on: ubuntu-latest
+    name: Run CircleCI artifacts redirector
+    steps:
+      - name: GitHub Action step
+        id: step1
+        uses: larsoner/circleci-artifacts-redirector-action@master
+        with:
+          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          artifact-path: 0/_build/html/index.html
+          circleci-jobs: build_page
+          job-title: Click here to see a preview of the documentation.
+      - name: Array API preview
+        run: |
+          curl --fail ${{ steps.step1.outputs.url }} | grep $GITHUB_SHA