Update dev configuration: add comments

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/resources/application-dev.properties

@@ -1,5 +1,10 @@
 # Pekka Helenius <fincer89@hotmail.com>, Fjordtek 2020
 
+# Development configuration
+
+
+
+# Temporary, volatile database
 spring.h2.console.enabled = true
 spring.h2.console.path    = /h2-console
 spring.datasource.url     = jdbc:h2:mem:testdb