Assert tracker v2 incomplete documentation SDK1.7.0

[phil38]

Some helpful pictures referenced in documentation (asset_tracker_v2_description.rst) are missing:

missing at least:  figure:: /images/asset_tracker_v2_module_hierarchy.svg

[Øivind]

Hi,

The full documentation with images can be found here: 

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.7.0/nrf/applications/asset_tracker_v2/doc/asset_tracker_v2_description.html