doc: fix type alignment for CREATE TABLE in triggers

doc: fix type alignment for CREATE TABLE in triggers

Datatypes in CREATE TABLE statements in the examples were vertically
aligned in most cases, a few examples were unaligned with a single
space. This makes sure all examples on the same page are consistently
aligned.

Patch by Laurenz Albe with some additional fixups by me.

Author: Laurenz Albe <laurenz.albe@cybertec.at>
Reported-by: lemes.marcelo26@gmail.com
Discussion: https://postgr.es/m/166870885664.635.16667004450401573487@wrigleys.postgresql.org