[IMP] marketing: match the Display Timezone description with tooltips

Issue:

The current descriptions and naming of the `Date` fields (`date_begin`,
`date_end`) and the `Timezone` field (`date_tz`) can be confusing in the
form view of the event model. Specifically:

The timezone used for converting the form dates to the database is
determined by the context and not by the `Timezone` field present on the
form. However, this `Timezone` field determines the timezone used
for displaying the event's date/time on the website. This change
clarifies the situation according to the update done in the community PR

opw-4323142

closes #11790

X-original-commit: fe9d186
Related: odoo/odoo#194354
Signed-off-by: Lancelot Semal (lase) <[email protected]>

content/applications/marketing/events/create_events.rst

@@ -62,10 +62,10 @@ The following are fields found on an event form:
      pop-up window appears, displaying various pre-configured language translation options available
      in the database.
 
-- :guilabel:`Date`: when the event is scheduled to take place. This field is auto-populated, but
-  modifiable, and is **required**.
-- :guilabel:`Timezone`: the corresponding timezone related to the event. This field is
-  auto-populated, but modifiable, and is **required**.
+- :guilabel:`Date`: when the event is scheduled to take place (expressed in your local timezone).
+  This field is auto-populated, but modifiable, and is **required**.
+- :guilabel:`Display Timezone`: the timezone in which the event dates/times will be displayed on the
+  website. This field is auto-populated, but modifiable, and is **required**.
 - :guilabel:`Language`: designate a specific language for all event communications to be translated
   into, if necessary. This field is blank, by default, so if event-related communications are being
   sent to recipients who speak a different language, be sure to configure this field properly.