Clear typos

ros2/navigation_overview.md

@@ -7,7 +7,7 @@
 The ROS 2 Navigation Stack or Nav2 is a motion planning and control framework for the mobile base. It is a stack because it encompasses several ROS packages that help with mapping, localization, planning and navigation. Stretch's mobile base has been integrated and works well right out of the box with Nav2.
 
 ## Motivation
-Stretch has a differential drive mobile base that enables navigation. However, before Stretch can navigate, it must be able to generate a map, localize itself in the environment and plan a path between points. This is challenging when the environment could present challenges such as static or dynamic obstacles that can get in the way of the robot, or floor surfaces with different frictional properties that can trip a controller.
+Stretch has a differential drive mobile base that enables navigation. However, before Stretch can navigate, it must be able to generate a map, localize itself in the environment and plan a path between points. This is challenging when the environment could present complexities such as static or dynamic obstacles that can get in the way of the robot, or floor surfaces with different frictional properties that can trip a controller.
 
 Fortunately, the Nav2 stack enables these capabilities through various packages and provides a simple Python API to interact with them. Let’s take a quick tour!
 
@@ -27,7 +27,7 @@ Once a map has been generated, Stretch can localize itself and find its way in i
   <img height=500 src="https://user-images.githubusercontent.com/97639181/206606699-9f3b87b1-a7d1-4074-b68a-2e880fc576a3.gif"/>
 </p>
 
-### Simple Commander Python API:
+### Simple Commander Python API
 It is as simple to interact with Nav2 programmatically, thanks to the Python API. For example, have a look at this neat patrol demo.
 
 <p align="center">