don't know about where the distribution is

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.5/static/tutorial-sql-intro.html
Description:

In this chapter it said

"
Examples in this manual can also be found in the PostgreSQL source
distribution in the directory src/tutorial/. (Binary distributions of
PostgreSQL might not compile these files.)
"

But I didn't see there is a 'tutorial' directory in my ubuntu system. Do I
need to create one and download the distribution to the folder? But it is
not the accurate meaning of what the tutorial is talking about.