Update robotstack.md

Author: zzx9636

Host_Setup/RoboStack/robotstack.md

@@ -6,7 +6,7 @@ RoboStack has released a new version of ROS Noetic. It uses a more recent versio
 ```
 ./ros_conda_install_unix_new.sh
 ```
-It will create a new environment called ```ros_base2```. You can activate it by ```conda activate ros_base2```. Your old environment ```ros_base``` will still be there.
+It will create a new environment called ```ros_base2```. You can activate it by ```conda activate ros_base2```. Your old environment ```ros_base``` will still be there. Both will work well for this class.
 
 ## Mac OS and Linux
 If you are using Mac OS or Linux, we provide you a simple script to automate the process. Simply open a terminal, then run
@@ -15,7 +15,7 @@ If you are using Mac OS or Linux, we provide you a simple script to automate the
 chmod +x ros_conda_install_unix.sh
 ./ros_conda_install_unix.sh
 ```
-If you already have conda (anaconda/miniconda/miniforge, etc) installed, it will install [**mamba**](https://mamba.readthedocs.io/en/latest/installation.html) in your base environments, and then create a new python3.9 environment with ROS Noetic installed.
+If you already have conda (anaconda/miniconda/miniforge, etc) installed, it will install [**mamba**](https://mamba.readthedocs.io/en/latest/installation.html) in your base environments, and then create a new python3.9 environment with ROS Noetic installed. If your original conda is very old, you might experience siginificantly slow installation and even errors. It might be a good idea to backup your old conda environments and use mambaforge.
 
 If you do not have conda installed, the script will first install [**mambaforge**](https://github.com/conda-forge/miniforge#mambaforge), and then create a new ROS Noetic environment.