Add missing QLDoc

Author: atorralba

java/ql/lib/semmle/code/java/frameworks/Thrift.qll

@@ -25,6 +25,7 @@ class ThriftIface extends Interface {
     this.getFile() instanceof ThriftGeneratedFile
   }
 
+  /** Returns an implementation of a method of this interface. */
   Method getAnImplementingMethod() {
     result.getDeclaringType().(Class).getASupertype+() = this and
     result.overrides+(this.getAMethod()) and

java/ql/lib/semmle/code/java/frameworks/struts/StrutsAnnotations.qll

@@ -15,6 +15,7 @@ class StrutsAnnotation extends Annotation {
 class StrutsActionAnnotation extends StrutsAnnotation {
   StrutsActionAnnotation() { this.getType().hasName("Action") }
 
+  /** Returns a callable annotated with this annotation. */
   Callable getActionCallable() {
     result = this.getAnnotatedElement()
     or