add unsupported info

Signed-off-by: Nitish Bharambe <nitish.bharambe@alliander.com>

docs/converters/vision_converter.md

@@ -44,6 +44,8 @@ Some components are yet to be modeled for conversions because they might not hav
 - The source bus in power-grid-model is mapped with a source impedance. `Sk"nom`, `R/X` and `Z0/Z1` are the attributes used in modeling source impedance. In Vision, these attributes are used only for short circuit calculations
 - The load rate for transformer is calculated in Vision by current i.e., `load_rate = max(u1 * I1, u2 * I2) * sqrt(3) / Snom * 100`. Whereas in power-grid-model, loading is calculated by power, i.e., `loading = max(s1,s2)/sn`. (Note: The attribute names are as per relevant notation in Vision and PGM respectively). This gives a slight difference in load rate of transformer.
 - A minor difference in results is expected since Vision uses a power mismatch in p.u. as convergence criteria whereas power-grid-model uses voltage mismatch.
+- The Voltage Control option in vision is modelled by `transoformer_tap_regulator` in PGM. Currently, PGM only supports line drop compesnation on both loading and generating direction.
+So the unchecking of `Also in backw. direction`. `Load Dependent` compensation and a master-slave configuration for control under the `State` section is not supported.
 
 ## Accomdation of UUID-based id system since Vision 9.7
 Vision introduced UUID based identifier system since version 9.7. It is implemented following the Microsoft naming scheme by replacing all the original identifier fields (i.e., '*Number', '*Subnumber', '*Nummber' and '*Subnummer') to GUID. This change brings the many benefits of UUIDs in general while on the other hand adds certain work on the conversion side. Since computations in PGM alone do not benefit from a string based identifier, we hence made the descision to perform UUID to integer conversion while maintaining the 'GUID' information in the `extra_info` field. Note that existing mapping files can still be used without significant changes, apart from adding `GUID` to the `extra` fields of interest.