Update SortedSet`1.xml (#10977)

Correct upper bount for ExceptWith.

Author: maa

xml/System.Collections.Generic/SortedSet`1.xml

@@ -1074,7 +1074,7 @@
 ## Remarks
  This method removes any element in the current <xref:System.Collections.Generic.SortedSet%601> that is also in `other`. Duplicate values in `other` are ignored.
 
- This method is an `O(n)` operation, where `n` is the number of elements in the `other` parameter.
+ This method is an `O(n log m)` operation, where `m` is <xref:System.Collections.Generic.SortedSet%601.Count%2A> and `n` is the number of elements in `other`.