Document LSMVector index

[robfrank]

ArcadeDB ha a new vector index using JVector library undeerneath

Code samples:

https://github.com/ArcadeData/arcadedb/blob/main/engine/src/test/java/com/arcadedb/index/vector/LSMVectorIndexTest.java

Issue and PR

ArcadeData/arcadedb#2529

ArcadeData/arcadedb#2816

rewrite the documentation section about Vector index using the new api and SQL in the examples