Removed garden from setup-gazebo docs

Signed-off-by: Saurabh Kamat <[email protected]>

Author: sauk2

setup_gazebo_in_ci.md

@@ -15,7 +15,6 @@ The action currently supports all the non-EOL Gazebo releases. See [releases](ht
 
 * Citadel
 * Fortress
-* Garden
 * Harmonic
 * Ionic
 

setup_gazebo_in_ci_macos.md

@@ -9,7 +9,6 @@ The `setup-gazebo` GitHub Action on macOS runners takes in the following paramet
 * `required-gazebo-distributions`: A **required** parameter that specifies the Gazebo distribution to be installed. The allowed keywords are,
   * `citadel`
   * `fortress`
-  * `garden`
   * `harmonic`
   * `ionic`
 

setup_gazebo_in_ci_ubuntu.md

@@ -9,7 +9,6 @@ The `setup-gazebo` GitHub Action on Ubuntu runners takes in the following parame
 * `required-gazebo-distributions`: A **required** parameter that specifies the Gazebo distribution to be installed. The allowed keywords are,
   * `citadel`
   * `fortress`
-  * `garden`
   * `harmonic`
   * `ionic`
 * `use-gazebo-prerelease`: An **optional** parameter to install pre-release binaries from OSRF repository.

setup_gazebo_in_ci_windows.md

@@ -9,7 +9,6 @@ The `setup-gazebo` GitHub Action on Windows runners takes in the following param
 * `required-gazebo-distributions`: A **required** parameter that specifies the Gazebo distribution to be installed. The allowed keywords are,
   * `citadel`
   * `fortress`
-  * `garden`
   * `harmonic`
   * `ionic`