Document the new `get-all-elts` method.
Document the new `get-all-elts` method.

AmeBel/atomspace,rTreutlein/atomspace,rTreutlein/atomspace,AmeBel/atomspace,rTreutlein/atomspace,AmeBel/atomspace,rTreutlein/atomspace,AmeBel/atomspace,rTreutlein/atomspace,AmeBel/atomspace