change default resource_class from small to medium

[angelisamaria]

free customers are unable to utilize resource_class: small therefore are blocked due to free-plan-resource-class-unavailable, changing resource_class: medium will allow free customers to utilize the orb

Checklist

• [x] All new jobs, commands, executors, parameters have descriptions
• [x] Examples have been added for any significant new features
• [x] README has been updated, if necessary

Motivation, issues

free customers are unable to utilize the resource_class key and therefore are blocked due to the error free-plan-resource-class-unavailable, changing resource_class: medium will allow free customers to utilize this orb

Description

change default resource_class from small to medium

[KyleTryon]

This issue has been resolved. Thank you.