add library to general machine learning list

Feature-engine is a sklearn compatible API with the widest toolset for feature engineering and selection.

Features:

    320k + downloads per month
    2k+ github stars
    50 contributors
    10k+ doc views per month

What is this Python project?

Most exhaustive collection of transformers for feature engineering including: imputation, categorical encoding, discretization, transformation, feature creation.

Feature engine also contains the widest library of feature selection methods after sklearn.

What's the difference between this Python project and similar ones?

The feature selection methods are not present elsewhere in the python ecosystem.

Many of the feature transformation and creation methods are also not present in other python libraries.

It enriches sklearn capabilities dramatically by adding additional tools to transform and select variables.

Author: solegalli

README.md

@@ -345,6 +345,7 @@ These are some Machine Learning and Data Mining algorithms and models help you t
 * [scikit-image](https://github.com/scikit-image/scikit-image)
 * [scikit-opt](https://github.com/guofei9987/scikit-opt)
 * [scikit-posthocs](https://github.com/maximtrp/scikit-posthocs)
+* [feature-engine](https://feature-engine.trainindata.com/)
 * [pystruct](https://github.com/pystruct/pystruct)
 * [Shogun](https://www.shogun-toolbox.org/)
 * [xLearn](https://github.com/aksnzhy/xlearn)