- Data sets adjustments

- Added a NEWS.md file to track changes to the package.

Included

`viral`

and`sero`

datasets for testing and demonstrating package functionality.Implemented

`knn_domain_score`

function for calculating domain applicability scores based on K-Nearest Neighbor models.Implemented

`mars_domain_score`

function for calculating domain applicability scores based on Multivariate Adaptive Regression Splines models.Implemented

`nn_domain_score`

function for calculating domain applicability scores based on Neural Network models.Implemented

`simple_domain_plot`

function to generate a domain plot for a simple model based on PCA distances. This function provides a visual representation of the domain applicability for the given data.Implemented

`rf_domain_score`

function for calculating domain applicability scores based on Random Forest models.Implemented

`normalized_domain_plot`

function to generate a domain plot for a normalized model based on PCA distances.