Doc: fix typos.
"PGcon" should be "PGconn".  Noted by D. Frey.
Discussion:
@@ -449,7 +449,7 @@ pg_int64 lo_tell64(PGconn *conn, int fd);
<indexterm><primary>lo_truncate</primary></indexterm>
To truncate a large object to a given length, call
<synopsis>
-int lo_truncate(PGcon *conn, int fd, size_t len);
+int lo_truncate(PGconn *conn, int fd, size_t len);
</synopsis>
This function truncates the large object
descriptor <parameter>fd</parameter> to length <parameter>len</parameter>. The
@@ -477,7 +477,7 @@ int lo_truncate(PGcon *conn, int fd, size_t len);
When dealing with large objects that might exceed 2GB in size,
instead use
<synopsis>
-int lo_truncate64(PGcon *conn, int fd, pg_int64 len);
+int lo_truncate64(PGconn *conn, int fd, pg_int64 len);
</synopsis>
This function has the same
behavior as <function>lo_truncate</function>, but it can accept a
