Update README

Author: geo

README.md

@@ -51,6 +51,12 @@ You can easily add a new skill in two steps.
 ## Desicion Model
 ![alt text](https://github.com/ggeop/Jarvis/blob/master/imgs/desicion_model.png)
 
+## Extract skill
+The skill extraction implement in a matrix of [TF-IDF features](https://scikit-learn.org/stable/modules/generated/sklearn.feature_extraction.text.TfidfVectorizer.html) for each skill.
+In the following example he have a dimensional space with three skills.
+The user input analyzed in this space and by using a similarity metric (e.g cosine) we find the most similar skill.
+![alt text](https://github.com/ggeop/Jarvis/blob/master/imgs/skill_space_desicion.png)
+
 ## Getting Started
 ### Create KEYs for third party APIs
 Jarvis assistant uses third party APIs for speech recognition,web information search, weather forecasting etc.