Review of new Core ML Tools public API docstrings, part 1

[cpompeo]

This PR reviews and makes edits to 10 of the 17 new docstrings in the Core ML Tools public API reference guide

Change summary

• Fix typos, ill-formatted links, and prose that did not match Apple style
• Normalize spelling of "lookup table" and "k-means operation" in non-code text
• Make description and arguments of ModuleSKMPalettizerConfig and ModulePostTrainingPalettizerConfig be the same, per Nehal Bhandari's guidance

Modified docstrings

2 docstrings related to the state feature:

• StateType: https://apple.github.io/coremltools/source/coremltools.converters.mil.input_types.html#coremltools.converters.mil.input_types.StateType ,
• make_state API: https://apple.github.io/coremltools/source/coremltools.models.html#coremltools.models.model.MLModel.make_state

2 docstrings related to the multiple function feature

• MultiFunctionDescriptor class: https://apple.github.io/coremltools/source/coremltools.models.html#coremltools.models.utils.MultiFunctionDescriptor
• save_multifunction : https://apple.github.io/coremltools/source/coremltools.models.html#coremltools.models.utils.save_multifunction

6 docstrings related to palettization

• ModulePostTrainingPalettizerConfig : https://apple.github.io/coremltools/source/coremltools.optimize.torch.palettization.html#coremltools.optimize.torch.palettization.ModulePostTrainingPalettizerConfig
• PostTrainingPalettizer : https://apple.github.io/coremltools/source/coremltools.optimize.torch.palettization.html#coremltools.optimize.torch.palettization.PostTrainingPalettizer
• PostTrainingPalettizerConfig: https://apple.github.io/coremltools/source/coremltools.optimize.torch.palettization.html#coremltools.optimize.torch.palettization.PostTrainingPalettizerConfig
• ModuleSKMPalettizerConfig: https://apple.github.io/coremltools/source/coremltools.optimize.torch.palettization.html#coremltools.optimize.torch.palettization.ModuleSKMPalettizerConfig
• SKMPalettizer: https://apple.github.io/coremltools/source/coremltools.optimize.torch.palettization.html#coremltools.optimize.torch.palettization.SKMPalettizer
• SKMPalettizerConfig: https://apple.github.io/coremltools/source/coremltools.optimize.torch.palettization.html#coremltools.optimize.torch.palettization.SKMPalettizerConfig

Next steps

After this PR is approved and merged, I'll run the make html script from the gh-pages branch and put up a PR in that branch so the changes can go live on the website.