typo: Double word "empty"

Author: nschonni

docs/xquery/aggregate-functions-avg.md

@@ -37,7 +37,7 @@ fn:avg($arg as xdt:anyAtomicType*) as xdt:anyAtomicType?
 ## Remarks  
  All the types of the atomized values that are passed to **avg()** have to be a subtype of exactly one of the three built-in numeric base types or xdt:untypedAtomic. They cannot be a mixture. Values of type xdt:untypedAtomic are treated as xs:double. The result of **avg()** receives the base type of the passed in types, such as xs:double in the case of xdt:untypedAtomic.  
 
- If the input is statically empty empty is implied and a static error is raised.  
+ If the input is statically empty, empty is implied and a static error is raised.  
 
  The **avg()** function returns the average of the numbers computed. For example: