Update README.md

Author: dgarijo

README.md

@@ -79,7 +79,7 @@ You are done!
 
 error: legacy-install-failure
 ```
-The try to update the python-dev utilities: `sudo apt-get install python3.X-dev` (where X is your python version)
+Then try to update the python-dev utilities: `sudo apt-get install python3.X-dev` (where X is your python version)
 
 ### Installation from code