Doc: remove annotations about multi-row output of set-returning functions.

I thought this added clarity, or at least was consistent with the way
these entries looked before v13 ... but apparently I'm in the minority.

Discussion: https://postgr.es/m/CAFj8pRAXuetiHUfs73zjsJD6B78FWcUsBS-j23sdCMFXkgx5Fg@mail.gmail.com

doc/src/sgml/func.sgml

@@ -3164,7 +3164,6 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
  {bar}
  {baz}
 </programlisting>
-        (2 rows in result)
        </para></entry>
       </row>
 
@@ -3225,7 +3224,6 @@ repeat('Pg', 4) <returnvalue>PgPgPgPg</returnvalue>
  hello
  world
 </programlisting>
-        (2 rows in result)
        </para></entry>
       </row>
 
@@ -17821,7 +17819,6 @@ SELECT NULLIF(value, '(none)') ...
  1
  2
 </programlisting>
-        (2 rows in result)
        </para></entry>
       </row>