[documentation] change wording from "Open..." to "Switch to..."

[buckyster]

Suggestion: In the documentation (e.g. Firefox extension homepage, Manage Extensions Shortcuts page, etc), change the wording for:

Open last used tab -> Switch to last used tab
Open last used window -> Switch to last used window

The reason is because "Open" implies opening a new tab or new window ("open file", "open link", etc). Whereas "Switch To" implies switching to an existing tab or window.

Because of this, I thought it was duplicating Firefox's ctrl+shift+T, which opens the last closed tab, and missed out on this feature for a long time. It's super useful when you have many tabs and windows open, but need to toggle between 2 of them!