[FIX] website_slides: fix website description field
This commit adds the parameter "sanitize_overridable=True" to the
"description" field of "website_slides" slides. It means that the
description can now be properly edited as an user with enough rights.
The issue is that the "slide.description" field is sanitized after
saving a "slide/*" page, which removes "<button>" elements. This is
not easily testable in version 16.0 because no blocks contain "<button>"
elements. However, starting from version 18.0, new blocks like the
"accordion" block include buttons, and these are removed after saving a
"slide/*" page when they are dropped into it.
opw-4273436
closes odoo/odoo#190620
Signed-off-by: Outagant Mehdi (mou) <[email protected]>
