slew_example.py: added to examples
in attitude_analysis.py: functions in utils.py and complement_missing_sofa.py are now embedded in attitude_analysis.py
use_rotation_matrices.py: utils.py and missing_complement_sofa.py imports removed
attitude_analysis.spacecraft_distance_from_a_point: fixed a minor bug, which caused the distance array to return empty.
requirements.txt: version numbers were added for dependencies.
.readthedocs.yaml: version number and installation instructions corrected