Update README.md

Author: ShadyDL

README.md

@@ -14,3 +14,10 @@ API Gateway for communication between the frontend and backend. Abstracts calls
 ```zsh
 docker-compose up --build
 ```
+
+#### Error: Docker Network Missing
+If you get the following error:
+Network `ipost-network` declared as external, but could not be found. Run the following:
+```zsh
+docker network create ipost-network
+```