Removed old use cases

Description

I removed 3 use cases from the working directory as they do no fit in the use case list in #22 (closed), letting the config change use case and atmospheric calibration use cases. This includes:

• usecases/IRF_catB_calib.md
• usecases/catc_reprocessing.md
• usecases/real_data_catB_calib.md

Related Issue

Closes #29 (closed)

Types of changes

• New Use Case
• Change request implementation