Add mention of http module in the website

[proneon267]

Since, we already know that v has a functional http module. Hence, http module should be mentioned in https://vlang.io/modules

[Water261]

Kind of ironic considering that in the modules page it list the http module when pulling offline copies of the modules pages

[JalonSolov]

The new Modules page - https://modules.vlang.io/ - lists all the standard V modules. You can find http under net (since it is a submodule of net).