[IMP] payment_provider/mercado pago: content updates

This commit will add important clarifications to use and test the Mercado Pago payment provider and add visual documentation similar to other provider's documentation

closes odoo/documentation#5525

Signed-off-by: Audrey Vandromme (auva) <auva@odoo.com>
Co-authored-by: samueljlieber <sali@odoo.com>

content/applications/finance/payment_providers/mercado_pago.rst

@@ -21,6 +21,9 @@ Configuration on Mercado Pago Dashboard
    If you are trying Mercado Pago as a test, select :guilabel:`Credienciales de prueba` in the left
    part of the application page, then copy the test :guilabel:`Access token`.
 
+.. image:: mercado_pago/mp-credentials.png
+   :alt: Production and testing credentials in Mercado Pago.
+
 .. _payment_providers/mercado_pago/configure_odoo:
 
 Configuration on Odoo
@@ -29,8 +32,9 @@ Configuration on Odoo
 #. :ref:`Navigate to the payment provider Mercado Pago <payment_providers/add_new>` and change its
    state to :guilabel:`Enabled`.
 #. In the :guilabel:`Credentials` tab, fill in the :guilabel:`Access Token` with the value you saved
-   at the step :ref:`payment_providers/mercado_pago/configure_dashboard`.
+   at the :ref:`payment_providers/mercado_pago/configure_dashboard` step.
 #. Configure the rest of the options to your liking.
 
 .. seealso::
-   :doc:`../payment_providers`
+   - :doc:`../payment_providers`
+   - `Mercado Pago Odoo webinar <https://www.youtube.com/watch?v=CX8vPHMb1ic>`_