fix(experience): parse diminished returns value from correct field

[TheBentoBox]

ExperienceConfig was attempting to parse the min diminished returns value from a field named Dimished_Returns, while the field in the config is correctly named Diminished_Returns. This means that, with diminished returns enabled, the config field is essentially ignored and diminished returns always use the default 0.05.

This corrects the config to parse using the correct field name.

[nossr50]

Thank you.