Update book.md

docs/features/book.md

@@ -8,7 +8,7 @@ Feature group | Feature type | Data type | Available for node types | Used by vi
 [`Sectional`](featuresbygroup.md#sectional-features) | [`Node`](featuresbyfeaturetype.md#node-features) | [`string`](featuresbydatatype.md#string-datatype) | [`word`](featuresbynodetype.md#word-nodes) [`group`](featuresbynodetype.md#group-nodes) [`wg`](featuresbynodetype.md#wg-nodes) [`chapter`](featuresbynodetype.md#chapter-nodes) [`sentence`](featuresbynodetype.md#sentence-nodes) [`verse`](featuresbynodetype.md#verse-nodes)  [`book`](featuresbynodetype.md#book-nodes) | [`syntax-view`](../syntax-view.md#start) [`wg-view`](../wg-view.md#start)
 ## Feature description
 
-Book name (full) 
+Book name (full) in the format as it is used by the [Bible Online Learner (Bible OL)](https://learner.bible/).
 
 ## Feature values