Update version in README.md (#43)

Author: shenxianpeng

README.md

@@ -75,7 +75,7 @@ jobs:
 
 #### `version`
 
-- **Description**: The desired version of the clang tools to use. Accepted options are strings which can be 6.0, 7, 8, 9, 10, 11, or 12.
+- **Description**: The desired version of the [clang-tools](https://hub.docker.com/repository/docker/xianpengshen/clang-tools) to use. Accepted options are strings which can be 6.0, 7, 8, 9, 10, 11, 12 or 13.
 - Default: '10'
 
 #### `verbosity`