Porting the upstream changes replaced snippets/indexing.mdx with a hand
copy from lancedb/docs, which dropped six exports the vector-index page
still imports (`mint validate` warns on each) and added
PyQuantizationCustomParams, which had no source here.
The quantization test region is ported from lancedb/docs and the module
is regenerated, so every export comes from a test again. The regenerated
PyQuantizationCustomParams matches the copy byte for byte. Also fixes
"convetion" and "entires" on the page.
Brendan Clement
b87c4de53b