Update paper and docs with entity_placement

[hammer]

It appears that Figure 1 and schema.html are out of date.

When I query the current release of GrapAL, the WITH_ENTITY relationship has a property named entity_placement, not position. The property values are odd, too; I see two different strings values ['0'] and ['1']. I presume there's some kind of upstream issue where you're representing an array as a string, but it would be nice in future releases to make this property take integer values.