update readme for iron

Signed-off-by: Kenji Brameld <[email protected]>

README.md

@@ -10,10 +10,10 @@ See [ijnek/gz_control_hw_demo](https://github.com/ijnek/gz_control_hw_demo) for
 
 ROS 2 version | Gazebo version | Branch
 -- | -- | --
-Galactic | Edifice (default) | [galactic](https://github.com/ijnek/gz_control_hw/tree/galactic)
-Galactic | Fortress | [galactic](https://github.com/ijnek/gz_control_hw/tree/galactic)
-Humble | Fortress (default) | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
-Humble | Garden | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
+Humble | Fortress (default) | [humble](https://github.com/ijnek/gz_control_hw/tree/humble)
+Humble | Garden | [humble](https://github.com/ijnek/gz_control_hw/tree/humble)
+Iron | Fortress (default) | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
+Iron | Garden | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
 Rolling | Edifice | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
 Rolling | Fortress (default) | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
 Rolling | Garden | [rolling](https://github.com/ijnek/gz_control_hw/tree/rolling)
@@ -45,8 +45,8 @@ The following steps are for Linux and OSX.
     source /opt/ros/rolling/setup.bash
 
     # Clone repoitory (**select one** from below, depending on your ROS 2 distro)
-    git clone https://github.com/ijnek/gz_control_hw.git -b galactic  # Galactic
-    git clone https://github.com/ijnek/gz_control_hw.git -b rolling  # Humble, Rolling
+    git clone https://github.com/ijnek/gz_control_hw.git -b humble  # Humble
+    git clone https://github.com/ijnek/gz_control_hw.git -b rolling  # Rolling
     ```
 
 1. Install dependencies (this may also install Ignition):