Docs: find_nearest pages still describe the list query path after #203 #249

#203 changed the native VectorIndex.find_nearest to send the query vector as one float32 buffer whatever its form (list, float64 array, float32 array). The docs still describe the older picture: the find_nearest section of how-to/vectors.adoc says nothing about how the query crosses, the "A query vector" section of how-to/databases-and-queries.adoc reads as if it covered find_nearest too, and the query_vector Args text in src/arcadedb/vector.py does not say that the native build converts any of the forms itself.

The native-versus-JVM vector query medians in the vector-search row of which-package.adoc were measured before #203, so they need a label saying so. The fix is a docs change, with the A/B figures from the #203 review in the find_nearest section.