fix ignore

Author: blink1073

.github/workflows/validate.yml

@@ -83,7 +83,7 @@ jobs:
            --check-links-ignore "/" \
            --check-links-ignore "https://www.nyu.edu/" \
            --check-links-ignore ".github/images/netlify-preview.png" \
-           --check-links-ignore ".*help.medium.com.*"
+           --check-links-ignore ".*help.medium.com.*" \
            --check-links-ignore "https:/twitter.com/.*"
 
   lighthouse: