create extension requires superuser?

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/10/sql-createextension.html
Description:

https://www.postgresql.org/docs/10/sql-createextension.html
"For most extensions this means superuser or database owner privileges are
needed"
(this is the same text for version 12, but I haven't tried that version.)

If I create a database, I can't CREATE EXTENSION postgis;
unless I'm superuser.  Is this bad documentation or is it just for this
extension?
It should be documented how to tell.