Fix spelling "radiants" -> "radians"

In English without the "t" 😉

src/robofish/io/entity.py|68 col 138| "Converting orientations, from a bigger range than [0, 2 * pi]. When passing the orientations, they are assumed to be in radiants."
tests/robofish/io/test_file.py|161 col 35| # Create an entity, using radiants
tests/robofish/io/test_file.py|164 col 41| # Read the poses of the file as radiants
tests/robofish/io/test_file.py|175 col 35| # Create an entity, using radiants
examples/example_readme.py|23 col 53| # Since it is a 3 column array, orientations in radiants are assumed.
docs/entity.md|26 col 28| # Creating an entity using radiant orientations.
docs/entity.md|34 col 26| # Create an entity using radiant orientations
docs/entity.md|42 col 43| # Here we create 4 fishes from poses with radiant orientation
docs/index.md|49 col 49| # Since it is a 3 column array, orientations in radiants are assumed.
README.md|46 col 49| # Since it is a 3 column array, orientations in radiants are assumed.