Fix duplicated word

Co-authored-by: Jason Desrosiers <[email protected]>

Author: handrews

jsonschema-validation.xml

@@ -950,7 +950,7 @@
 
                 <t>
                     If the instance value is a string, this property defines that the string
-                    SHOULD be interpreted as encoded binary data and, and applications wishing
+                    SHOULD be interpreted as encoded binary data and applications wishing
                     to decode it SHOULD do so using the encoding named by this property.
                 </t>