Adding minimal README

Author: aentinger

README.md

@@ -0,0 +1,29 @@
+ArduinoDebugUtils
+=================
+
+This class provides functionality useful for debugging sketches via `printf`-style statements.
+
+# How-To-Use Basic
+ArduinoDebugUtils has 6 different debug levels (described descending from highest to lowest priority):
+* `DebugLevel::None` - no debug output is shown
+* `DebugLevel::Error` - critical errors
+* `DebugLevel::Warning` - non-critical errors
+* `DebugLevel::Info` - information
+* `DebugLevel::Debug` - more information
+* `DebugLevel::Verbose` - most information
+
+The desired debug level can be set via `setDebugLevel(DebugLevel::Warning)`.
+
+Debug messages are written via `debugPrint` which supports `printf`-style formatted output.
+
+Example:
+```C++
+int i = 1;
+float pi = 3.1459;
+ArduinoDebugUtils.debugPrint(DebugLevel::Verbose, "i = %d, pi = %f, i, pi);
+```
+
+If desired timestamps can be prefixed to the debug message. Timestamp output can be enabled and disabled via `timestampOn` and `timestampOff`.
+
+# How-To-Use Advanced
+Normally all debug output is redirected to the primary serial output of each board (`Serial`). In case you want to redirect the output to another output stream you can make use of `setDebugOutputStream(&Serial2)`.