Bug and fix in 2_Slithering_Snake.ipynb

[TenguBoss]

Aloha Elastica Team.

Thank you for posting Jupyter notebooks.

The loop in compute_projected_velocity() is one too long. I have changed line 22 from
# for i in range(1, number_of_period - 1):
to
for i in range(1, number_of_period - 2):
to fix it.

Regards,
BU

[Ali-7800]

@TenguBoss Thanks for letting us know about this, we fixed the bug and fix would be released with the next update