[CronJob] Add notes to CronJob entity #62

Job	Run time
After Split Testing of application	38s
After Split Testing of aws-tool-kit	53s
After Split Testing of console	51s
After Split Testing of core	43s
After Split Testing of cron-job	54s
After Split Testing of doctrine-extra	39s
After Split Testing of entity-migrator	54s
After Split Testing of fixer	50s
After Split Testing of framework-extra-bundle	1m 0s
After Split Testing of log	47s
After Split Testing of mailer	42s
After Split Testing of messenger	41s
After Split Testing of open-api	46s
After Split Testing of process	48s
After Split Testing of profiling	56s
After Split Testing of security	53s
After Split Testing of sonata-import-bundle	48s
After Split Testing of sonata-integration-bundle	47s
After Split Testing of sonata-extra-bundle	46s
After Split Testing of tester	42s
After Split Testing of tester-bundle	43s
After Split Testing of user-bundle	53s
After Split Testing of validator	48s
After Split Testing of workflow	47s
	19m 9s

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