DOCSP-35957: Retrieve guide (#2722)

Author: norareidy

docs/index.txt

@@ -13,7 +13,9 @@ Laravel MongoDB
    :titlesonly:
    :maxdepth: 1
 
+   /install
    /quick-start
+   /retrieve
    /eloquent-models
    /query-builder
    /user-authentication
@@ -50,6 +52,7 @@ Fundamentals
 To learn how to perform the following tasks by using the {+odm-short+},
 see the following content:
 
+- :ref:`laravel-fundamentals-retrieve`
 - :ref:`laravel-eloquent-models`
 - :ref:`laravel-query-builder`
 - :ref:`laravel-user-authentication`