Change default entry page for add-ons

In Tor Browser menu, when you click the Add-ons the first time, it will show you the Get Add-ons tab and it automatically connects to Mozilla servers.

While installing add-ons is not recommended and automatic connections to Mozilla isn't good at all it's better to change the entry page using the following code:

user_pref("extensions.ui.lastCategory", "addons://list/extension");