docs: fix no parameter connect string example (#1056)
docs: fix no parameter connect string example (#1056)

postgresql-42.1.4 - DriverManager.getConnection("jdbc:postgresql:/") throws org.postgresql.util.PSQLException: FATAL: database "/" does not exist. The trailing slash is being interpreted as the database name. DriverManager.getConnection("jdbc:postgresql:") connects to the default port on localhost using the user's name as the database.
marschall/pgjdbc,davecramer/pgjdbc,zapov/pgjdbc,golovnin/pgjdbc,davecramer/pgjdbc,whitingjr/pgjdbc,pgjdbc/pgjdbc,zapov/pgjdbc,golovnin/pgjdbc,marschall/pgjdbc,marschall/pgjdbc,AlexElin/pgjdbc,pgjdbc/pgjdbc,lordnelson/pgjdbc,zapov/pgjdbc,golovnin/pgjdbc,pgjdbc/pgjdbc,whitingjr/pgjdbc,AlexElin/pgjdbc,sehrope/pgjdbc,whitingjr/pgjdbc,sehrope/pgjdbc,marschall/pgjdbc,jorsol/pgjdbc,pgjdbc/pgjdbc,sehrope/pgjdbc,AlexElin/pgjdbc,davecramer/pgjdbc,lordnelson/pgjdbc,sehrope/pgjdbc,lordnelson/pgjdbc,jorsol/pgjdbc,jorsol/pgjdbc,davecramer/pgjdbc,jorsol/pgjdbc