Fix some nonstandard capitalization.

Ashutosh Bapat

doc/src/sgml/ddl.sgml

@@ -2907,8 +2907,8 @@ VALUES ('Albany', NULL, NULL, 'NY');
 
      <listitem>
       <para>
-       Since Primary Keys are not supprtable on partitioned tables
-       Foreign keys referencing partitioned tables are not supported, nor
+       Since primary keys are not supported on partitioned tables
+       foreign keys referencing partitioned tables are not supported, nor
        are foreign key references from a partitioned table to some other table.
       </para>
      </listitem>