Document impact of the uniqueness constraint on memory footprint

[antejavor]

10 milion nodes with application ID = 1GB (approximately)
10 milion nodes with index on application ID = 2 GB (approximately)
10 milion nodes with a constraint on the application ID = 3GB (approximately)
Scaling this by a factor of 10:
100M nodes = 10GB
100M nodes + index = 20GB
100M nodes + index + constraint = 30GB
Scaling this by a factor of 10
1B = 100GB
1B nodes + index = 200GB
1B nodes + index + constraint = 300GB

Expand the memory calculation with the context on uniqueness constraints: https://memgraph.com/docs/fundamentals/storage-memory-usage#calculate-storage-memory-usage