add mongodb to spring boot code example

Example 1: spring boot mongo crud repository application properties

# Application configuration.
server.port=8102
 
# Local mongodb configuration.
spring.data.mongodb.host=localhost
spring.data.mongodb.port=27017
spring.data.mongodb.database=ducat-assignment

Example 2: connecting to mongo database in spring boot

spring.data.mongodb.uri: mongodb://<hostInformation>/<DatabaseName>