Fix typo in Concept 16 of Modular Algebra

[Howard]

Description

There is a typo in the video and notebook used in the concept 16 lesson (https://courses.openmined.org/courses/foundations-of-private-computation/50502950-48c7-488c-b6d8-ea512b7fd84f/4d261b23-c978-421c-aeeb-08394339fd51). The typo is also surfaced in this discussion: #312.

Expected Behavior

Change

For random 𝑎 the probability for it not being a witness is 25%, therefore the probability of not finding 10 witnesses at random if 𝑎 is composite is 0.25^10, i.e. If no witnesses are found in 10 rounds, then the probability for 𝑎 being prime is 1−0.2510= 0.999999

to

For random 𝑎 the probability for it not being a witness is 25%, therefore the probability of not finding 10 witnesses at random if n is composite is 0.25^10, i.e. If no witnesses are found in 10 rounds, then the probability for n being prime is 1−0.2510= 0.999999