Add link to RTD build for PRs (#1786)

Create a message in PR with link to the PR's ReadTheDocs before it's merged.

Fixes #1610

.github/workflows/docs.yaml

@@ -9,11 +9,16 @@ on:
       - release/*
     paths:
       - docs/**
-  pull_request:
-    types: [opened, reopened, synchronize]
+  pull_request_target:
+    types: [issues, opened, reopened, synchronize]
 
 jobs:
+
   documentation:
+
+    permissions:
+      pull-requests: 'write'
+
     runs-on: ubuntu-latest
     name: Build and deploy documentation
 
@@ -49,3 +54,17 @@ jobs:
         path: artifact/doc_warnings.log
         if-no-files-found: ignore
 
+    - name: Comment ReadDocs
+      uses: actions/github-script@v6
+      with:
+        script: |
+          const message = `
+          Link to ReadTheDocs sample build for this PR can be foune at:
+          https://global-workflow--${{ github.event.pull_request.number }}.org.readthedocs.build/en/${{ github.event.pull_request.number }}
+          `
+          github.rest.issues.createComment({
+           issue_number: context.issue.number,
+           owner: context.repo.owner,
+           repo: context.repo.repo,
+           body: message 
+          })