Improve example and README

[shunichironomura]

• Add print statement ignore rule to lint config
• Update default name in UncaughtExceptionWatcher init
• Update default value of allow_dirty to True
• Update default name in TimeWatcher constructor
• Update default check value in CommandContext to True
• Update default value of abort_on_error to True
• Refactor logging to print in calculate_pi function
• Simplify context setup in capsula.toml configuration
• Reformat capsula.toml
• Remove empty line in capsula.toml
• Update README with usage and feature changes
• Remove pre_run_capsule from calculate_pi function