Added documnetation in Readme.md

Author: sanujkul

README.md

@@ -27,3 +27,41 @@ If desired timestamps can be prefixed to the debug message. Timestamp output can
 
 # 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)`.
+
+# Documentation
+### 1. Debug :   
+Arduino_DebugUtils Object that will be used for calling member functions.  
+
+### 2. Debug.setDebugLevel(int const debug_level) :
+Parameter debug_level in order of lowest to highest priority are : `DBG_NONE`, `DBG_ERROR`, `DBG_WARNING`, `DBG_INFO` (default), `DBG_DEBUG`, and `DBG_VERBOSE`.  
+Return type: void.  
+Example:
+```
+Debug.setDebugLevel(DBG_VERBOSE);
+```
+
+### 2. Debug.setDebugOutputStream(Stream * stream) : 
+By default, Output Stream is Serial. In advanced cases other objects could be other serial ports (if available), or can be a Software Serial object.
+Example:
+```
+SoftwareSerial mySerial(10, 11); // RX, TX
+...
+Debug.setDebugOutputStream(&mySerial);
+```
+
+### 3. Debug.timestampOn() :  
+Calling this function will switches on the timestamp in `Debug.print()` function call;
+By default, printing timestamp is off, unless turned on using this function call.
+
+### 4. Debug.timestampOff() :  
+Calling this function will switches off the timestamp in `Debug.print()` function call;
+
+### 5. Debug.print(int const debug_level, const char * fmt, ...);
+This function assess the debug_level and prints the message if parameter `debug_level` in `Debug.print(debug_level, ...)` function call belongs to the range: DBG_ERROR <= debug_level <= (<DBG_LEVEL> that has been set using setDebugLevel() function).
+Example:
+```
+Debug.setDebugLevel(DBG_VERBOSE);
+int i = 0;
+Debug.print(DBG_VERBOSE, "DBG_VERBOSE i = %d", i);
+
+```