Server Framework 101, Basic views links to tree example

[RoelAdriaans]

In the basic views, tree is replaced by list. But the example links to an old commit, where tree is still used.

Offending line:

documentation/content/developer/tutorials/server_framework_101/06_basicviews.rst

Line 47 in a2af035

`here <https://github.com/odoo/odoo/blob/6da14a3aadeb3efc40f145f6c11fc33314b2f15e/addons/crm/views/crm_lost_reason_views.xml#L46-L54>`__.

[AntoineVDV]

Hi @RoelAdriaans, thanks for the notice! I'm closing the issue because the Server Framework 101 tutorial is being completely rewritten, and the example link will soon be removed.