updated a broken link and renamed script files for mysql

src/main/resources/db/mysql/petclinic_db_setup_mysql.txt

@@ -19,6 +19,6 @@
 3) Create the PetClinic database and user by executing the "db/mysql/createDB.txt"
    script.
 
-4) Open "src/main/resources/jdbc.properties"; comment out all properties in the
+4) Open "src/main/resources/spring/jdbc.properties"; comment out all properties in the
    "HSQL Settings" section; uncomment all properties in the "MySQL Settings"
    section.
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