[FEATURE] Create detection rule | Add more descriptive error message

[jovancacvetkovic]

Is your feature request related to a problem?

• The description field error message is "Invalid description."
• Author field error message is "Invalid author."
• Rule status field shows as required after clicking the delete button but still says experimental.

What solution would you like?
Add a more descriptive error message, like with the Rule name field: "Rule name must contain 5-50 characters. Valid characters are a-z, A-Z, 0-9, hyphens, spaces, and underscores."

Do you have any additional context?