Swift: Remove some redundant statements in a few of the QLDoc comments.

Author: geoffw0

swift/ql/lib/codeql/swift/security/CleartextLoggingExtensions.qll

@@ -13,9 +13,6 @@ abstract class CleartextLoggingBarrier extends DataFlow::Node { }
 
 /**
  * A unit class for adding additional flow steps.
- *
- * Extend this class to add additional flow steps that should apply to paths related to
- * cleartext logging of sensitive data vulnerabilities.
  */
 class CleartextLoggingAdditionalFlowStep extends Unit {
   /**

swift/ql/lib/codeql/swift/security/PathInjectionExtensions.qll

@@ -17,9 +17,6 @@ abstract class PathInjectionBarrier extends DataFlow::Node { }
 
 /**
  * A unit class for adding additional flow steps.
- *
- * Extend this class to add additional flow steps that should apply to paths related to
- * path injection vulnerabilities.
  */
 class PathInjectionAdditionalFlowStep extends Unit {
   /**

swift/ql/lib/codeql/swift/security/PredicateInjectionExtensions.qll

@@ -12,9 +12,6 @@ abstract class PredicateInjectionBarrier extends DataFlow::Node { }
 
 /**
  * A unit class for adding additional flow steps.
- *
- * Extend this class to add additional flow steps that should apply to paths related to
- * predicate injection vulnerabilities.
  */
 class PredicateInjectionAdditionalFlowStep extends Unit {
   /**