Add separate version notes for scalars

Add separate version notes for scalars

Add separate 1.4.24 and 1.4.26 version notes for the .scalars method;
this covers Session, scoped_session, AsyncSession, async_scoped_session
as the "scoped" versions did not have the method added until 1.4.26
as part of :ticket:`7103`.

Also indicate scoped_session as ``sqlalchemy.orm.scoped_session`` in
docs rather than ``sqlalchemy.orm.scoping.scoped_session``.  This is
also happening in I77da54891860095edcb1f0625ead99fee89bd76f separately,
as both changesets refer to scoped_session without using ".scoping".

References: #7103
Closes: #9371
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/9371
Pull-request-sha: 61132230cc6e897ab61beff25d98b19a4c0aefd0

Change-Id: I84c8b1aad752db124cfee6bc8516f6eed7ba2faf