feat: add development instructions

HACKING.md

@@ -0,0 +1,17 @@
+# Hacking
+
+## 1. Setting up development environment
+
+Expects a Postgres database with the following setup:
+
+1. user = postgres
+2. password = password
+3. database name = password
+
+The following Docker command will download and run Postgres with the
+above mentioned configuration
+
+```bash
+export db=z-payments-postgress && \
+docker create --name $db -e POSTGRES_PASSWORD=password -p 5432:5432 postgres  && docker start $db
+```