Because you can't place bookmarklets in github descriptions. Please go to the Github Page to grab the button.
NICE: Editor is an easy way to change the text on your website for a quick visual prototype or copy editor.
This is a javascript bookmarklet and of course, only lives in the browser. Refreshing the page will reset all changes.
To edit any page, just click the bookmark in your bookmarks bar. That will disable the links and javascript and put into edit mode. For more options, click the expander arrow.
This button will toggle between your current edited HTML, and the original.
This button will generate a diff of the changes made. All additions are in green, and all removals are in red.
This button will remove the NICE button, and reset the DOM configuration. However, it will keep your changes.
Important to note that javascript can make this process difficult. There are sites that the toggle won't work on. And also, the diff could find extra issues. I will keep coming up with cases to help minimize these, but unfortunately, its just part of it.
The editing should work on all pages though.
NICE: Editor Works in all major modern browsers. Meaning, I have not tested IE. But it should work in 9+.