Update README.md

README.md

 # xeyes sentences
 
+*xeyes sentences* allow you to display the sentence you want using xeyes program. 
+
 ## How to use it ?
 
+Clone this project and run :
 ```
 cd src
 python xeyes_sentences your_sentence
 cd ..
 ./xeyes_sentences.sh
-```
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+```
+
+NB : you may need the execution right to run the script `chmod +x xeyes_sentences.sh`
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