Update µBlock Firefox add-on page

[devnoname120]

Hello,

Would it be possible to update the Firefox add-on page every time a release is made?

The releases on Github don't have an auto-update feature, and the add-on page is outdated, so I need to manually install the new version from Github.

[gorhill]

Duplicate of #1006.

[devnoname120]

@gorhill Why not adding a <updateURL> in install.rdf? It would be set to something like https://ublock.github.io/latest.rdf when released on Github.