convert autolink into url macro

This allows to add the final period.

Author: jnavila

book/B-embedding-git/sections/dulwich.asc

@@ -40,5 +40,5 @@ porcelain.log('.', max_entries=1)
 
 ==== Further Reading
 
- * The official API documentation is available at https://www.dulwich.io/docs/api/
+ * The official API documentation is available at https://www.dulwich.io/docs/api/[].
  * Official tutorial at https://www.dulwich.io/docs/tutorial[] has many examples of how to do specific tasks with Dulwich.