[doc] Nits with builtin::trim

[grr]

Where

builtin::trim

Description

1. Don't suggest String::Util. it uses suboptimal implementations throughout, If you need to suggest an alternative, builtin::compat is a good candidate, name included. It also has better backwards compatibliity: 5.8 vs. String::Util's 5.14.

2. Don't propagate the slower combined regex. Instead of:

$str =~ s/\A\s+|\s+\z//urg;

use:
s/\A\s+//u, s/\s+\z//u for my $copy = $str;

[jesuslozanomosterin]

IMHO To the perlfaq chatper adecuate.