Replace to use correct name

I believe Mozilla has been pretty consistent to calling it Firefox Developer Tools ([1](https://wiki.mozilla.org/DevTools), [2](https://hacks.mozilla.org/2013/11/reintroducing-the-firefox-developer-tools-part-2-the-scratchpad-and-the-style-editor/), [3](https://hacks.mozilla.org/2013/11/live-editing-webgl-shaders-with-firefox-developer-tools/), [4](https://hacks.mozilla.org/2012/09/html-editing-and-other-improvements-in-firefox-17-developer-tools/), and [5](https://developer.mozilla.org/en-US/docs/Tools))