created get absolute url method under Book models

lancedamalerio_reading/bookshelf/models.py

 from django.db import models
+from django.urls import reverse
 
 #Author
 #first_name; last_name; age; nationality; bio
@@ -27,4 +28,8 @@ class Book(models.Model):
     def __str__(self):
         return self.title 
     
+    def get_absolute_url(self):
+        return(reverse('bookshelf:book-details', kwargs={'pk' : self.pk}))
+
+