Swift: Query description.

Author: geoffw0

swift/ql/src/queries/Security/CWE-135/StringLengthConflation.ql

@@ -1,6 +1,6 @@
 /**
  * @name String length conflation
- * @description TODO
+ * @description Using a length value from an `NSString` in a `String`, or a `count` from a `String` in an `NSString`, may cause unexpected behavior.
  * @kind problem
  * @problem.severity TODO
  * @security-severity TODO