[Docs] Add Release Notes for 19.10
[Docs] Add Release Notes for 19.10

Resolves: LE-13747
Change-Id: I35e095206cc24fa50628305eaaea7082feb1f616

legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af,legatoproject/legato-af