Merge pull request #14 from thedadams/sub-tool-doc

chore: add subTool option to README

Author: thedadams

README.md

@@ -25,6 +25,7 @@ None of the options is required, and the defaults will reduce the number of call
 - `cacheDir`: Specify the cache directory.
 - `quiet`: No output logging
 - `chdir`: Change current working directory
+- `subTool`: Use tool of this name, not the first tool
 
 ## Functions