Fix/maintenance window task

[GlennChia]

Issue #, if available:

Description of changes:

• Sync JSON example with the YAML changes in #1180. In this case, TaskInvocationParameters do not support MaxConcurrency, MaxErrors, and Priority attributes. Reference: AWS::SSM::MaintenanceWindowTask TaskInvocationParameters
• Fix alignment of attributes for MaintenanceWindowAutomationParameters in the YAML example. Reference: AWS::SSM::MaintenanceWindowTask MaintenanceWindowAutomationParameters
• Style fixes by removing trailing whitespaces

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