fix: app absolute path in production

Author: josecelano

README.md

@@ -17,7 +17,7 @@ The application is located in the directory: `/home/torrust/github/torrust/torru
 To run docker compose commands you need to cd to the app dir:
 
 ```console
-cd github/torrust/torrust-demo/
+cd /home/torrust/github/torrust/torrust-demo
 ```
 
 Sample commands:

share/bin/deploy-torrust-demo.com.sh

@@ -2,8 +2,8 @@
 
 # Update the demo by updating the containers
 
-cd github/torrust/torrust-demo/
+cd /home/torrust/github/torrust/torrust-demo || exit
 docker compose pull
 docker compose down
 docker compose up --build --detach
-cd ~
+cd ~ || exit