Update ReadMe.md

ReadMe.md

@@ -12,13 +12,13 @@ This driver offers a c++ wrapper to control a pan&tilt [PTU-D46](https://www.sus
  * Move both servos on torque mode.
  * Get any feedback that the pna-tilt offers.
 
-On the following image is shown a pan&tilt and his controller:
+On the following image is shown a pan&tilt and its controller:
 
 <img src="doc/images/ptu_d46.png" alt="ptu_d46" height="150">
 
 ## Instalation
 
-If the labrobotica repository was already added to your computer, it is only necessary the third command:
+If the labrobotica's repository was already added to your computer, is only necessary the third command:
 
 ``` sudo sh -c 'echo "deb [arch=amd64] http://147.83.76.226/~irilabo/packages xenial main" > /etc/apt/sources.list.d/labrobotica_repo.list' ```