Fix "Good Beginner Bugs" link
Fix "Good Beginner Bugs" link

Seems like the label was changed and the link needs to be updated
timvandermeij/pdf.js,timvandermeij/pdf.js,showpad/mozilla-pdf.js,Shoobx/pdf.js,nawawi/pdf.js,Shoobx/pdf.js,timvandermeij/pdf.js,Snuffleupagus/pdf.js,mozilla/pdf.js,nawawi/pdf.js,nawawi/pdf.js,showpad/mozilla-pdf.js,showpad/mozilla-pdf.js,Shoobx/pdf.js,mozilla/pdf.js,Snuffleupagus/pdf.js,Snuffleupagus/pdf.js,mozilla/pdf.js