[Doc] Move PR template content to docs (#10159)

Signed-off-by: Russell Bryant <rbryant@redhat.com>

.github/scripts/cleanup_pr_body.sh

@@ -15,19 +15,36 @@ NEW=/tmp/new_pr_body.txt
 gh pr view --json body --template "{{.body}}" "${PR_NUMBER}" > "${OLD}"
 cp "${OLD}" "${NEW}"
 
-# Remove all lines after and including "**BEFORE SUBMITTING, PLEASE READ THE CHECKLIST BELOW AND FILL IN THE DESCRIPTION ABOVE**"
-sed -i '/\*\*BEFORE SUBMITTING, PLEASE READ THE CHECKLIST BELOW AND FILL IN THE DESCRIPTION ABOVE\*\*/,$d' "${NEW}"
-
 # Remove "FIX #xxxx (*link existing issues this PR will resolve*)"
 sed -i '/FIX #xxxx.*$/d' "${NEW}"
 
 # Remove "FILL IN THE PR DESCRIPTION HERE"
 sed -i '/FILL IN THE PR DESCRIPTION HERE/d' "${NEW}"
 
+# Remove all lines after and including "**BEFORE SUBMITTING, PLEASE READ THE CHECKLIST BELOW AND FILL IN THE DESCRIPTION ABOVE**"
+sed -i '/\*\*BEFORE SUBMITTING, PLEASE READ.*\*\*/,$d' "${NEW}"
+
+# Remove HTML <details> section that includes <summary> text of "PR Checklist (Click to Expand)"
+python3 - <<EOF
+import re
+
+with open("${NEW}", "r") as file:
+    content = file.read()
+
+pattern = re.compile(r'(---\n\n)?<details>.*?<summary>.*?PR Checklist \(Click to Expand\).*?</summary>.*?</details>', re.DOTALL)
+content = re.sub(pattern, '', content)
+
+with open("${NEW}", "w") as file:
+    file.write(content)
+EOF
+
 # Run this only if ${NEW} is different than ${OLD}
 if ! cmp -s "${OLD}" "${NEW}"; then
-    echo "Updating PR body"
     gh pr edit --body-file "${NEW}" "${PR_NUMBER}"
+    echo
+    echo "Updated PR body:"
+    echo
+    cat "${NEW}"
 else
     echo "No changes needed"
 fi