Add logo to the Container Description(Notes)

[modbus2mqtt]

Currently, All containers created by the community scripts show the community script logo and refer to the community script github...
This is good.

However, a configurable logo for the app would be nice.
The build.func description function could get an optional parameter containing the logo url.
This could be placed near the existing logo.

Thus, it's easier to distinguish the different nodes.

What do you think?