[SPARK-16485][ML][DOC] Fix privacy of GLM members, rename sqlDataTypes for ML, doc fixes

## What changes were proposed in this pull request?

Fixing issues found during 2.0 API checks:
* GeneralizedLinearRegressionModel: linkObj, familyObj, familyAndLink should not be exposed
* sqlDataTypes: name does not follow conventions. Do we need to expose it?
* Evaluator: inconsistent doc between evaluate and isLargerBetter
* MinMaxScaler: math rendering --> hard to make it great, but I'll change it a little
* GeneralizedLinearRegressionSummary: aic doc is incorrect --> will change to use more common name

## How was this patch tested?

Existing unit tests.  Docs generated locally.  (MinMaxScaler is improved a tiny bit.)

Author: Joseph K. Bradley <joseph@databricks.com>

Closes #14187 from jkbradley/final-api-check-2.0.