Doc: fix examples for pg_input_error_info().

These were causing "contents ... exceed the available area"
warnings in PDF builds, and also didn't quite follow our markup
conventions for function examples.  To fix the overwidth
problem, reduce the number of fields shown in one example,
and also insert &zwsp; to let the header line be broken in
a reasonable place.

Discussion: https://postgr.es/m/20230324194701.dqkzcdtlcikseo22@awork3.anarazel.de

doc/src/sgml/func.sgml

@@ -24902,7 +24902,7 @@ SELECT collation for ('foo' COLLATE "de_DE");
        <para>
         Tests whether the given <parameter>string</parameter> is valid
         input for the specified data type; if not, return the details of
-        the error would have been thrown.  If the input is valid, the
+        the error that would have been thrown.  If the input is valid, the
         results are NULL.  The inputs are the same as
         for <function>pg_input_is_valid</function>.
        </para>
@@ -24914,16 +24914,21 @@ SELECT collation for ('foo' COLLATE "de_DE");
         directly.
        </para>
        <para>
+        <literal>select * from pg_input_error_info('42000000000', 'integer')</literal>
+        <returnvalue></returnvalue>
 <programlisting>
-SELECT * FROM pg_input_error_info('42000000000', 'integer');
                        message                        | detail | hint | sql_error_code
 ------------------------------------------------------+--------+------+----------------
  value "42000000000" is out of range for type integer |        |      | 22003
-
-SELECT * FROM pg_input_error_info('1234.567', 'numeric(7,4)');
-        message         |                                      detail                                       | hint | sql_error_code
-------------------------+-----------------------------------------------------------------------------------+------+----------------
- numeric field overflow | A field with precision 7, scale 4 must round to an absolute value less than 10^3. |      | 22003
+</programlisting>
+       </para>
+       <para>
+        <literal>select message, detail from pg_input_error_info('1234.567', 'numeric(7,4)')</literal>
+        <returnvalue></returnvalue>
+<programlisting>
+        message         |                                      detail
+------------------------+----------------------------------&zwsp;-------------------------------------------------
+ numeric field overflow | A field with precision 7, scale 4 must round to an absolute value less than 10^3.
 </programlisting>
        </para></entry>
       </row>