Update README.md

Author: ahmedmoustafa

README.md

@@ -35,7 +35,7 @@ sudo docker run -it bioinformatics-toolbox
 ```
 
 ### Notes
-- The size of the image is about **60 GB**.
+- The size of the image is about **20 GB**.
 - Pulling the image (option #1) takes about **50 minutes** on a Google Cloud machine type [**e2-medium**](https://cloud.google.com/compute/docs/machine-types) in zone [**us-west2-a**](https://cloud.google.com/compute/docs/regions-zones).
 - Building the image (option #2) takes about **six hours** on a Google Cloud machine type [**e2-medium**](https://cloud.google.com/compute/docs/machine-types) in zone [**us-west2-a**](https://cloud.google.com/compute/docs/regions-zones).