Typo in XPointer draft

In the 3rd bullet point pof section 4.3, "A n XPointer part that does 
not locate" should be "An XPointer part that does not locate". i.e. 
delete the extra space in "A n".

-- 
+-----------------------+------------------------+-------------------+
| Elliotte Rusty Harold | elharo@metalab.unc.edu | Writer/Programmer |
+-----------------------+------------------------+-------------------+ 
|               Java I/O (O'Reilly & Associates, 1999)               |
|            http://www.ibiblio.org/javafaq/books/javaio/            |
|   http://www.amazon.com/exec/obidos/ISBN=1565924851/cafeaulaitA/   |
+----------------------------------+---------------------------------+
|  Read Cafe au Lait for Java news:  http://www.cafeaulait.org/      | 
|  Read Cafe con Leche for XML news: http://www.ibiblio.org/xml/     |
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