Documentation for public custom types is sourced in metadata of properties/methods that use them

[sbethur]

Description of issue

There are custom types that are accepted/returned by public methods:

• WaveformInfo by fetch, fetch_into, and read methods in niscope
• MeasurementStats by fetch_measurement_stats method in niscope
• HistoryRAMCycleInformation by fetch_history_ram_cycle_information method in nidigital
• LCRLoadCompensationSpot and LCRMeasurement (Soon-to-be-added methods in nidcpower will use these)

In the current code generator design, when generating the documentation for the properties/methods that use them, the docstring defined for the custom types are not used, but rather the docstring embedded in the metadata of the properties/methods are used.
e.g.: Documentation for fetch: https://nimi-python.readthedocs.io/en/master/niscope/class.html#fetch (See the return value)
The source for documentation:

nimi-python/src/niscope/metadata/functions.py

Line 1303 in 3dda150

'description': '\nReturns a list of class instances with the following timing and scaling information about each waveform:\n\n- **relative_initial_x** (float) the time (in seconds) from the trigger to the first sample in the fetched waveform\n- **absolute_initial_x** (float) timestamp (in seconds) of the first fetched sample. This timestamp is comparable between records and acquisitions; devices that do not support this parameter use 0 for this output.\n- **x_increment** (float) the time between points in the acquired waveform in seconds\n- **channel** (str) channel name this waveform was acquired from\n- **record** (int) record number of this waveform\n- **gain** (float) the gain factor of the given channel; useful for scaling binary data with the following formula:\n\n .. math::\n\n voltage = binary data * gain factor + offset\n\n- **offset** (float) the offset factor of the given channel; useful for scaling binary data with the following formula:\n\n .. math::\n\n voltage = binary data * gain factor + offset\n\n- **samples** (array of float) floating point array of samples. Length will be of the actual samples acquired\n'

Drawbacks of current design:

• Creation and maintenance of the custom type documentation is cumbersome
• If the same type is used by multiple API, then we need to duplicate the documentation strings

[sbethur]

FYI @olsl21, your PRs - #1771 and #1772 will be impacted by this.