restore readme

Signed-off-by: Adam Gutglick <adam@spiraldb.com>

Author: AdamGS

vortex-duckdb/README.md

@@ -18,26 +18,20 @@ Link against the precompiled DuckDB release build.
 cargo build -p vortex-duckdb
 ```
 
-Build the C-compatible DuckDB extension artifacts with:
-
-```bash
-cargo build -p vortex-duckdb-extension
-```
-
 ### Debug Build
 
 Opt into DuckDB debug build: `VX_DUCKDB_DEBUG=1`.
 
 ```bash
-VX_DUCKDB_DEBUG=1 cargo build -p vortex-duckdb-extension
+VX_DUCKDB_DEBUG=1 cargo build -p vortex-duckdb
 ```
 
 ### AddressSanitizer & ThreadSanitizer
 
 Enable both ASAN & TSAN: `VX_DUCKDB_SAN=1`.
 
 ```bash
-VX_DUCKDB_DEBUG=1 VX_DUCKDB_SAN=1 cargo build -p vortex-duckdb-extension
+VX_DUCKDB_DEBUG=1 VX_DUCKDB_SAN=1 cargo build -p vortex-duckdb
 ```
 
 ## Environment Variables