resolve warnings in `generate-docs`

[wowtor]

/home/wb/workspace/libraries/lir/lir/aggregation/base.py:docstring of lir.aggregation.base.AggregationData:7: WARNING: more than one target found for cross-reference 'LLRData': lir.LLRData, lir.data.models.LLRData [ref.python]
/home/wb/workspace/libraries/lir/lir/aggregation/base.py:docstring of lir.aggregation.base.AggregationData:13: WARNING: more than one target found for cross-reference 'LRSystem': lir.lrsystems.LRSystem, lir.lrsystems.lrsystems.LRSystem [ref.python]
/home/wb/workspace/libraries/lir/lir/aggregation/base.py:docstring of lir.aggregation.base.AggregationData:31: WARNING: more than one target found for cross-reference 'LRSystem': lir.lrsystems.LRSystem, lir.lrsystems.lrsystems.LRSystem [ref.python]
/home/wb/workspace/libraries/lir/docs/api/lir.aggregation.rst:2: WARNING: more than one target found for cross-reference 'DataProvider': lir.DataProvider, lir.data.models.DataProvider [ref.python]
/home/wb/workspace/libraries/lir/lir/aggregation/base.py:docstring of lir.aggregation.base.AggregationData:7: WARNING: more than one target found for cross-reference 'LLRData': lir.LLRData, lir.data.models.LLRData [ref.python]
/home/wb/workspace/libraries/lir/lir/aggregation/base.py:docstring of lir.aggregation.base.AggregationData:13: WARNING: more than one target found for cross-reference 'LRSystem': lir.lrsystems.LRSystem, lir.lrsystems.lrsystems.LRSystem [ref.python]
/home/wb/workspace/libraries/lir/lir/aggregation/base.py:docstring of lir.aggregation.base.AggregationData:31: WARNING: more than one target found for cross-reference 'LRSystem': lir.lrsystems.LRSystem, lir.lrsystems.lrsystems.LRSystem [ref.python]

etc...

See also:

• https://stackoverflow.com/questions/15115514/how-do-i-document-classes-imported-from-other-modules-hence-without-the-declar/31594545#31594545
• https://stackoverflow.com/questions/46263274/how-can-i-prevent-sphinx-from-displaying-the-full-path-to-my-class