docs: add note to pgvector docs that ext name is vector

apps/docs/content/guides/database/extensions/pgvector.mdx

@@ -6,6 +6,10 @@ description: 'pgvector: a PostgreSQL extension for storing embeddings and perfor
 
 [pgvector](https://github.com/pgvector/pgvector/) is a PostgreSQL extension for vector similarity search. It can also be used for storing [embeddings](https://supabase.com/blog/openai-embeddings-postgres-vector).
 
+<Admonition type="note">
+  The name of pgvector's Postgres extension is [vector](https://github.com/pgvector/pgvector/blob/258eaf58fdaff1843617ff59ea855e0768243fe9/README.md?plain=1#L64).
+</Admonition>
+
 Learn more about Supabase's [AI & Vector](/docs/guides/ai) offering.
 
 ## Concepts