Modify pg_vector version which supports PG18

Author: yuanyl630

CN/modules/ROOT/pages/master/5.2.adoc

@@ -35,7 +35,7 @@ export PG_CONFIG=/usr/local/ivorysql/ivorysql-4/bin/pg_config
 
 ** 拉取pg_vector源码
 ```
-git clone --branch v0.6.2 https://github.com/pgvector/pgvector.git
+git clone --branch v0.8.1 https://github.com/pgvector/pgvector.git
 ```
 
 ** 安装 pgvector