[DOCS] Missing RETURNS clause in function declaration

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/9.6/static/plpgsql-porting.html
Description:

I'm (very) new to PostgreSQL, so please forgive me if my findings are
incorrect...

On page https://www.postgresql.org/docs/9.6/static/plpgsql-porting.html, the
statement starting with CREATE OR REPLACE FUNCTION cs_parse_url (towards the
middle of the page) is missing the RETURNS clause.