Add 20-docs-in-doc-days links to the administration and atlas free tier setup pages

Author: kirbyk

source/administration.txt

@@ -12,11 +12,11 @@ includes both high level overviews of these concerns as well as
 tutorials that cover specific procedures and processes for operating
 MongoDB.
 
-.. admonition:: MongoDB Atlas
+.. note::
 
    For a simple way to run, monitor, and maintain cloud-hosted MongoDB
    deployments, try `MongoDB Atlas
-   <https://www.mongodb.com/cloud/atlas?jmp=docs>`_.
+   <https://www.mongodb.com/cloud/atlas?utm_source=administration&utm_campaign=20-docs-in-20-days&utm_medium=docs>`_.
 
 .. admin-introduction-end
 

source/tutorial/atlas-free-tier-setup.txt

@@ -8,11 +8,12 @@ Create an Atlas Free Tier Cluster
 
 .. default-domain:: mongodb
 
-`MongoDB Atlas <https://www.mongodb.com/cloud/atlas?jmp=docs>`_ is a cloud-hosted
-service for provisioning, running, monitoring, and maintaining MongoDB
-deployments. It is a fast, easy, and free way to get started with
-MongoDB. To install and run MongoDB locally, see
-:ref:`Install MongoDB<tutorial-installation>`.
+`MongoDB Atlas
+<https://www.mongodb.com/cloud/atlas?utm_source=atlas-free-tier-setup&utm_campaign=20-docs-in-20-days&utm_medium=docs>`_
+is a cloud-hosted service for provisioning, running, monitoring, and
+maintaining MongoDB deployments. It is a fast, easy, and free way to get
+started with MongoDB. To install and run MongoDB locally, see :ref:`Install
+MongoDB<tutorial-installation>`.
 
 .. tabs-top::