Fix broken env key in README.md

Signed-off-by: Kaur Palang <kaur.palang@brightcodecompany.com>

Author: kpalang

README.md

@@ -133,7 +133,7 @@ services:
     environment:
       - DATABASE=postgres
       - DATABASE_URL=jdbc:postgresql://db:5432/enginedb
-      - DATABASE_MAX_engineIONS=20
+      - DATABASE_MAX_CONNECTIONS=20
       - DATABASE_USERNAME=enginedb
       - DATABASE_PASSWORD=enginedb
       - DATABASE_MAX_RETRY=2