Add db config to README

Author: danlooo

README.md

@@ -20,6 +20,13 @@ pathtraits batch .
 pathtraits get foo.txt
 ```
 
+## Configuration
+
+### Database path
+
+The databse is being created in your home directory by default at "~/.pathtraits.db".
+One can change this by setting the environmental variable `PATHTRAITS_DB_PATH` to any other path with write permssions if needed.
+
 ## Developing
 
 - use Pylint