docs: fix PR title spellcheck (#1133)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

- **Chores**
  - Updated workflows to trigger on all pull request branches.
  - Enhanced PR title workflow to check spelling errors using `cspell`.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: Czaki

.github/workflows/check_pr_title.yml

@@ -7,6 +7,9 @@ on:
       - reopened
       - edited
       - synchronize
+  pull_request:
+    branches:
+      - '**'
 
 jobs:
   lint:
@@ -33,9 +36,10 @@ jobs:
 
       - name: Check PR title spelling
         env:
-          $PR_TITLE: ${{ github.event.pull_request.title }}
+          PR_TITLE: ${{ github.event.pull_request.title }}
         run: |
-          if ! cspell --words-only --no-progress <<< "$PR_TITLE"; then
+          echo "$PR_TITLE"
+          if ! cspell --no-progress stdin <<< "$PR_TITLE"; then
             echo "Spelling errors found in PR title"
             exit 1
           fi