updated README.md to reflect new logging paradigm.

README.md

@@ -93,6 +93,26 @@ please keep up with these changes, as they will not be backward compatible and r
     - [X] Data Types
     - [X] Session Tag
 
+## Verbosity ##
+Logging can be enabled and configured using the DEBUG_I2P environment variable. By default, logging is disabled.
+
+There are three available log levels:
+
+- Debug
+```shell
+export DEBUG_I2P=debug
+```
+- Warn
+```shell
+export DEBUG_I2P=warn
+```
+- Error
+```shell
+export DEBUG_I2P=error
+```
+
+If in case I2P_DEBUG is set to an unrecognized variable, it will fall back to "debug".
+
 ## Contributing
 
 See CONTRIBUTING.md for more information.