Document method wrappers which transform the `auto` value for a parameter

Start by reading httomo/method_wrappers/dezinging.py around lines 51–58 and httomo/method_wrappers/generic.py around lines 264–269. Identify the wrappers that accept auto for axis and document how each transforms it before calling the underlying method. Done means the wrapper documentation clearly explains the YAML value and the resulting method parameter type.

The auto value can be used for a few different parameters of different methods, such as:

• axis of a dezinger method wrapped by DezingingWrapper
  https://github.com/DiamondLightSource/httomo/blob/74b94c9140945211657617c00b7ff9694455d60d/httomo/method_wrappers/dezinging.py#L51-L58
• axis of an image saver method (though doesn't appear in the image saver wrapper, but in the generic wrapper)
  https://github.com/DiamondLightSource/httomo/blob/74b94c9140945211657617c00b7ff9694455d60d/httomo/method_wrappers/generic.py#L264-L269

The underlying methods from their respective libraries have the axis parameter which don't have auto as a possible value, but in httomo YAML pipeline config files we have introduced the ability to override the value of this axis parameter and have the associated wrapper transform the "auto" into something else on behalf of the users.

This results in the YAML config file for a method using the auto value presenting a different public API compared to the public API of the method function in its respective library (ie, its type signature): in httomo, the value of axis is presented to be able to be auto, but in the method function itself, the value of axis is an int. These will have different types:

• allowing axis to have a value of auto in addition to integers will have the type Union[Literal["auto"], int]
• allowing axis to only have an integer value will have type int

The method wrappers doing this transformation from auto to an int (which form the perspective of types is a conversion from a Union[Literal["auto"], int] to an int) aren't documented as doing so.

Documenting the method wrappers to at least have some information about the transformation being done can help mitigate confusion regarding the two conflicting public API's that are exposed by httomo's YAML config files vs. the method function's documentation.