Clearly document that generic reads can be lossy #288
Description
Currently the only mention of the lossy conversions is in the Usage section of the Tag docs.
Given how widely used read_from{_path} and Probe::read are used, it would be nice to warn that these will discard any items that cannot be expressed in a generic way. Should the warning dissuade the user from writing tags that are read using generic methods?
It might be nice to put the warning in the top level docs as well.