Release v1.6.0 (#324)

* Update version and changelog for v1.6.0
* Update docs
diff --git a/docs/dyn/books_v1.series.html b/docs/dyn/books_v1.series.html
index 52426c3..011b154 100644
--- a/docs/dyn/books_v1.series.html
+++ b/docs/dyn/books_v1.series.html
@@ -94,7 +94,7 @@
   An object of the form:
 
     {
-    "series": [ # Series info list. The client always expects this element in the JSON output, hence declared here as OutputAlways.
+    "series": [
       {
         "seriesId": "A String",
         "bannerImageUrl": "A String",