Ignition -> Gazebo (#396)

* update codecov badge
* ignition -> gazebo

Signed-off-by: Jenn Nguyen <jenn@openrobotics.org>

README.md

@@ -52,15 +52,15 @@ callback system.
 * **Graphics**: Collada, SVG, STL, OBJ, and DEM loaders. In-memory mesh,
   image, and material representations. Animation processing and BVH loader.
 * **Profiler**: A common profiler abstraction that can be used to measure and
-  visualize run time of various pieces of Gazebo robotics software.
+  visualize run time of various pieces of Gazebo software.
 
 # Install
 
-See the [installation tutorial](https://gazebosim.org/api/common/4.0/tutorials.html).
+See the [installation tutorial](https://gazebosim.org/api/common/3.11/tutorials.html).
 
 # Usage
 
-Please refer to the [examples directory](https://github.com/gazebosim/gz-common/raw/main/examples/).
+Please refer to the [examples directory](https://github.com/gazebosim/gz-common/tree/ign-common3/examples).
 
 # Folder Structure