Unity Answers $$anonymous$$ Fix oleh mattenaps

The Unity Answers forum has been scorched by a hack that replaced all instances of "hi" with the string "$$anonymous$$", and it sucks. This extensions restores the original text by doing a string replacement on the paragraph and span elements in javascript.

Inspired by the Chrome extension made by paolo pedercini (which you can find here: https://chrome.google.com/webstore/detail/unity-answers-anonymous-f/colofafhdnhgopgnbigiadgknpbgfcgk?hl=en&authuser=0)