Rationale:
The majority of cases where an ir.asset is manually declared
outside of manifest files is to specifically add a single asset file.
This means developers are specifying a single asset *path*, and not a
glob expression. In this context, it seems better to name the filepath
field `path`, and document that it can be specified with a glob
expression when (seldom) needed, rather than making the exception appear
to be the norm - possibly puzzling many developers (What's a glob and
why do I need one?)
The doc is updated as well, and some spell-checking and wording
improvements were done too.
This required some adaptations to the existing `ir.asset` declarations:
- odoo/enterprise#17465
- odoo/design-themes#459closesodoo/odoo#68695
Related: odoo/upgrade#2348
Signed-off-by: Olivier Dony (odo) <odo@openerp.com>