[Docs][Python][C++] Asof join documentation is wrong/incomplete

[hadrian-reppas]

Describe the bug, including details regarding any error messages, version, and platform.

There are two issues with the asof join docs:

1. In the doc for the on parameter, it says "a row is considered a match if and only if left_on - tolerance <= right_on <= left_on." This is incorrect because a join with positive tolerance results in right_on values that are greater than or equal to left_on. Also, the inequality does not make sense for negative tolerances.
2. In the doc for the tolerance parameter, it says "A right row is considered a match with the left row right.on - left.on <= tolerance." This does not mention that the difference must also be greater than or equal to 0. Also, the inequality is only correct for non-negative tolerances.

Component(s)

Python