Document using strokeCap(PROJECT) with point(), invisible points problem

[jeremydouglass]

Issue description

Currently it is unclear in documentation that strokeCap(SQUARE) does not cause points to become square -- instead, it causes the points to become invisible. You must use strokeCap(PROJECT) instead. See processing issues:

processing/processing#4871
processing/processing#5957

URL(s) of affected page(s)

https://processing.org/reference/strokeCap_.html
https://processing.org/reference/point_.html

Proposed fix

Add a brief note to each reference page clarifying how strokeCap() interacts with point().