Implement hero.describe(s), Closes #166

[henrifroese]

Straightforward implementation of description in #166 .

Example:

>>> import texthero as hero
>>> import pandas as pd
>>> df = pd.read_csv("https://raw.githubusercontent.com/jbesomi/texthero/master/dataset/bbcsport.csv")
>>> hero.describe(df["text"], df["topic"])
                                                                                              Value
number of documents                                                                             737
number of unique documents                                                                      727
number of missing documents                                                                       0
most common words                                          [the, to, a, in, and, of, for, ", I, is]
most common words excluding stopwords             [said, first, england, game, one, year, two, w...
average document length                                                                     387.803
length of shortest document                                                                     119
length of longest document                                                                     1855
standard deviation of document lengths                                                      210.728
25th percentile document lengths                                                                241
50th percentile document lengths                                                                340
75th percentile document lengths                                                                494
label distribution                     football                                            0.359566
                                       rugby                                               0.199457
                                       cricket                                              0.16825
                                       athletics                                           0.137042
                                       tennis                                              0.135685

Screenshot of pretty-printed output from Google Colab:

Note: only so many lines changed because this builds upon #157

[mk2510]

this branch is now based on the master and ready for review/to be merged 🦸 🦸‍♂️ 🦸‍♀️

[jbesomi]

Amazing, will check soon and let you know! 🎉 🎉