Update README.md

the command `vectors CASCADE` will include `pgvector` automatically.

README.md

@@ -57,7 +57,6 @@ Ensure extensions are enabled, connect to the database using the psql, and run t
 ```sql
 CREATE EXTENSION IF NOT EXISTS vchord CASCADE;
 CREATE EXTENSION IF NOT EXISTS pg_search CASCADE;
-CREATE EXTENSION IF NOT EXISTS vectors CASCADE;
 ```
         
 ## Uses