QVT — Consider using the package keyword instead of metamodel

In Section 8.4.5 Notation for metamodels, the keyword 'package' could be more appropriate
to represent nested packages within a metamodel definition or even a package containing
only tags

(1) In section 8.4.5, replace "A MOF Package is notated using the metamodel keyword followed by a name" by "A MOF Package is notated either using the 'package' keyword or the 'metamodel' keyword followed by a name. Both notations are equivalent when translating to the corresponding EMOF metamodel representation. The 'metamodel' keyword should preferably be used when referring to a top-level package that represents a complete metamodel.

For the impact in BNF grammar, see issue resolution for 10026.