polished instructions

README.md

@@ -4,7 +4,7 @@ This repository contains all presentations related to R3.
 
 # Preferred method
 
-<img src="https://webdav-r3lab.uni.lu/public/R3lab/logos/warning.png" height="20px" width="20px"> Install Docker first.
+<img src="https://webdav-r3lab.uni.lu/public/R3lab/logos/warning.png" height="20px" width="20px"> Install Docker first: https://docs.docker.com/install/
 
 Then, run:
 
@@ -13,6 +13,11 @@ $ ./contribute.sh -date "YYYY-MM-DD" -name "presentationName"
 $ ./contribute.sh -d YYYY-MM-DD -n presentationName
 ```
 Your slides are now in `YYYY/YYYY-MM-DD_presentationName/slides`.
+The first time, the underlying docker image will be downloaded (pulled). This may take a while.
+
+Once the slides have been compiled, a local server is running under http://localhost:9000. You may need to access this server under http://127.0.0.1:9000 or http://0.0.0.0:9000.
+
+In order to stop the execution, hit `CTRL+C`. Rerun the same command above to continue working on the presentation.
 
 **Example** for a Xmas presentation:
 ```bash