minor: typo correction

Author: corburn

source/faq/indexes.txt

@@ -140,7 +140,7 @@ How can I effectively use indexes strategy for attribute lookups?
 For simple attribute lookups that don't require sorted result sets or
 range queries, consider creating a field that contains an array of
 documents where each document has a field (e.g. ``attrib`` ) that
-holds a specific type of attribute. You can index this ``atrib``
+holds a specific type of attribute. You can index this ``attrib``
 field.
 
 For example, the ``attrib`` field in the following document allows you