Default description for Smartling isn't actually as useful as we thought

[stevejalim]

This description template

wagtail-localize-smartling/src/wagtail_localize_smartling/models.py

Lines 287 to 292 in e433366

	description = (
	"Automatically-created Wagtail translation job for "
	f"{ct_name} "
	f'"{source_instance}". '
	f"The source content can be edited here: {edit_url}"
	)

generate strings like

Automatically-created Wagtail translation job for simple rich text page "test testeststsesetstst". The source content can be edited here: /cms-admin/pages/105/edit/

Which is of very low value to a Smartling user, because they likely won't have access to the CMS admin.

I know we can override the description with a custom callback, but it might just be simpler to fix it here, given that no one will really get much value out of the default description