Incomplete sentence corrected. Resolves Issue #1997 (#2000)

* Incomplete sentence corrected. Issue #1997 

Resolves Issue #1997

``` FaceRecognizer::train(InputArrayOfArrays src, InputArray labels); ```

The type `InputArray` can accept `vector<T>` or `Mat` types as mentioned here: https://docs.opencv.org/3.4/d4/d32/classcv_1_1__InputArray.html

* Trailing whitespaces problem resolved