[dataimport] Add explanation about why external entities can't be inserted
By default after the import processed the importer indicates which external
entities can't be inserted because they are missing dependency data (other
entities, used in inlined or mandatory relations).
It usually helps there to find out which extids / relations are missing, so add
this to the log.
Tutorials
~~~~~~~~~
We present a few tutorials of different levels. The blog building
tutorial introduces one smoothly to the basic concepts.
Then there is a photo gallery construction tutorial which highlights
more advanced concepts such as unit tests, security settings,
migration scripts.
.. toctree::
:maxdepth: 1
base/index
advanced/index
tools/windmill.rst
textreports/index
dataimport/index