docs.yml: trigger workflow only on push to main

.github/workflows/docs.yml

@@ -1,12 +1,12 @@
 name: docs
 
-# Run this workflow when a review is requested on a PR that targets the master
-# branch, or the PR is closed
 on:
   push
+    branches: [main]
+# when a review is requested on a PR that targets `main`,
+# or the PR is closed:    
   # pull_request:
   #   types: [review_requested, closed]
-  #   branches: [master]
 
 # Prevent multiple PRs from building/deploying the docs at the same time
 concurrency:
@@ -43,9 +43,9 @@ jobs:
 
       # check code coverage, store results in the built docs.
       # coverage.py creates a .gitignore with '*' where it's run; remove it
-      # to keep the cooverage report and badge on gh-pages
+      # to keep the coverage report and badge on gh-pages
       - name: Coverage
-        # only continue if the PR is not just closed, but also merged
+        # only continue if the PR is not just closed, but also merged:
         # if: github.event.pull_request.merged == true
         run: |
           coverage run --source=py_template -m pytest test/*.py