BUG #14695: Documentation is not accurate

The following bug has been logged on the website:

Bug reference: 14695
Logged by: Jaroslav Sivy
Email address: yarex(at)pobox(dot)sk
PostgreSQL version: 9.6.3
Operating system: n/a
Description:

url: https://www.postgresql.org/docs/8.1/static/functions-math.html

CEIL and FLOOR example is not accurate.

ceil(dp or numeric)
smallest integer not less than argument: ceil(-42.8) = -42

..... well, minus 42 is not smallest integer from -42.8, because -42 is
bigger number :-).

..... so correct number should be -43 in case of negative numbers
(positive are fine)

Same applies to FLOOR from negative numbers, where its opposite.