fix comments

docs/manual-CN/2.query-language/4.statement-syntax/1.data-definition-statements/TTL.md

@@ -93,7 +93,7 @@ nebula> CREATE TAG t1(a int, b int, c string) ttl_duration = 100, ttl_col = "a";
 nebula> ALTER TAG t1 CHANGE (a string); -- failed
 ```
 
-- 注意一个 tag 或 edge 不能同时拥有 TTL 和索引，只能二者择其一，即使 `ttl_col` 配置的字段与要创建索引的字段不同。
+- 注意一个 tag 或 edge 不能同时拥有 TTL 和索引，只能二者择其一。
 
 ``` ngql
 nebula> CREATE TAG t1(a int, b int, c string) ttl_duration = 100, ttl_col = "a";

docs/manual-CN/3.build-develop-and-administration/2.install/1.install-with-rpm-deb.md

@@ -23,7 +23,7 @@
 
      * Centos 7: https://oss-cdn.nebula-graph.com.cn/package/${release_version}/nebula-${release_version}.el7-5.x86_64.rpm
 
-     * Centos 8: https://oss-cdn.nebula-graph.com.cn/package/${release_version}/nebula-${release_version}.el8-5.x86_64.rpm
+     * Centos 8: https://oss-cdn.nebula-graph.com.cn/package/${release_version}/nebula-${release_version}.el8.x86_64.rpm.rpm
 
      * Ubuntu 1604: https://oss-cdn.nebula-graph.com.cn/package/${release_version}/nebula-${release_version}.ubuntu1604.amd64.deb
 
@@ -44,7 +44,7 @@
     * Centos 6: https://oss-cdn.nebula-graph.com.cn/package/nightly/${date}/nebula-${date}-nightly.el6-5.x86_64.rpm
 
     * Centos 7: https://oss-cdn.nebula-graph.com.cn/package/nightly/${date}/nebula-${date}-nightly.el7-5.x86_64.rpm
-    * Centos 8: https://oss-cdn.nebula-graph.com.cn/package/nightly/${date}/nebula-${date}-nightly.el8-5.x86_64.rpm
+    * Centos 8: https://oss-cdn.nebula-graph.com.cn/package/nightly/${date}/nebula-${date}-nightly.el8.x86_64.rpm.rpm
 
     * Ubuntu 1604: https://oss-cdn.nebula-graph.com.cn/package/nightly/${date}/nebula-${date}-nightly.ubuntu1604.amd64.deb