Add database setup to "hacking" instructions

hacking.md

@@ -52,6 +52,11 @@ For each service *except* meta.sr.ht:
   `config.ini`, modifying it according to the comments.
 * `ln -s /path/to/meta.sr.ht/config.ini config.ini`
 
+For each `SERVICE`:
+
+* `createdb $SERVICE`
+* `./$SRV-initdb` (e.g. `./metasrht-initdb`)
+
 To run a service:
 
 * `./api/api`