Generate documentation based on annotations attached to classes and methods

Allow users to pass in a text file of the format:
   annotationname:Documentation String
   annotation2:More Documentation
that will get inserted into the docs when a class or method has
that annotation.

Bug: 19931569
Change-Id: Ic2334dd2fcba638526cf2d67e25e27cf8e39b6fe
diff --git a/src/com/google/doclava/MethodInfo.java b/src/com/google/doclava/MethodInfo.java
index eb360cd..f1659f3 100644
--- a/src/com/google/doclava/MethodInfo.java
+++ b/src/com/google/doclava/MethodInfo.java
@@ -592,6 +592,18 @@
       TypeInfo.makeHDF(data, base + ".generic.typeArguments", mTypeParameters, false);
     }
 
+    int numAnnotationDocumentation = 0;
+    for (AnnotationInstanceInfo aii : annotations()) {
+      String annotationDocumentation = Doclava.getDocumentationStringForAnnotation(
+          aii.type().qualifiedName());
+      if (annotationDocumentation != null) {
+        data.setValue(base + ".annotationdocumentation." + numAnnotationDocumentation + ".text",
+            annotationDocumentation);
+        numAnnotationDocumentation++;
+      }
+    }
+
+
     AnnotationInstanceInfo.makeLinkListHDF(
       data,
       base + ".showAnnotations",