update README.md

Author: funbringer

README.md

@@ -20,6 +20,8 @@ We encourage you to use `virtualenv` for your testing environment.
 
 ## Usage
 
+### Environment
+
 > Note: by default testgres runs `initdb`, `pg_ctl`, `psql` provided by `PATH`.
 
 There are several ways to specify a custom postgres installation:
@@ -35,6 +37,13 @@ python my_tests.py
 ```
 
 
+### Logging
+
+By default, `cleanup()` removes all temporary files (DB files, logs etc) that were created by testgres' API methods. If you'd like to keep logs, execute `configure_testgres(node_cleanup_full=False)` before running any tests.
+
+> Note: context managers (aka `with`) call `cleanup()` automatically.
+
+
 ### Overview
 
 Here is an example of what you can do with `testgres`: