[information_schema]: restored some translations; fixed some errors

Author: TsinghuaLucky912

postgresql/doc/src/sgml/information_schema.sgml

@@ -14056,7 +14056,7 @@ ________________________________________________________-->
 ________________________________________________________-->
      <row>
       <entry role="catalog_table_entry"><para role="column_definition">
-       <structfield>空值唯一</structfield> <type>是或否</type>
+       <structfield>nulls_distinct</structfield> <type>yes_or_no</type>
       </para>
       <para>
        如果约束是唯一约束，则<literal>是</literal>表示约束将空值视为不同，<literal>否</literal>表示约束将空值视为相同，否则对于其他类型的约束为null。