pg_doctestify Demo

This is a simple test, It doesn't do anything special.

select version();
                                                       version                                                       
---------------------------------------------------------------------------------------------------------------------
 PostgreSQL 17.5 (Debian 17.5-1.pgdg120+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 12.2.0-14) 12.2.0, 64-bit
(1 row)

Another simple thing

select * from generate_series(1, 10);
 generate_series 
-----------------
               1
               2
               3
               4
               5
               6
               7
               8
               9
              10
(10 rows)

The source for this test is sql/demo.sql. The rendered markdown is docs/demo.md