Notabug.org should be moved to B tier

[GMD Ephir]

Dear GNU,

notabug.org has fixed it's problems with javascript. Now 
https://notabug.org/js/semantic-2.2.13.min.js isn't used and all 
web-labels are up to date. See 
https://notabug.org/assets/librejs/librejs.html

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Gracefully, Ephir