Update README.md

Author: sergiopaniego

rl_studio/README.md

@@ -64,6 +64,12 @@ python rl-studio.py -f config/<config.yaml>
 ```
 where <config.yaml> can be any config you can create or previosly existed.
 
+When launching Gazebo, if you found and error, try killing all possible previous ROS-Gazebo processes:
+
+```
+killall gzserver
+killall gzclient
+```
 
 ## Config.yaml
 The config.yaml contains all project hyperparams and configuration needed to execute correctly. In case you want to train a Formula 1 agent in a Follow Lane task in Gazebo, with a PPO algorithm and Tensorflow Deep Learning framework, you can use next example from a config.yaml example file:
@@ -85,4 +91,4 @@ Remaining params should be adjusted too. There are many working yaml files in co
 > need extend the rl-studio.py to listen for inputs in a port and execute the loaded brain/algorithm to provide
 > outputs in the desired way.
 
-More info about how to config and launch any task, please go to [agents](agents/README.md) section.
+More info about how to config and launch any task, please go to [agents](agents/README.md) section.