added log doc

docs/lib-log.md

@@ -0,0 +1,46 @@
+# log
+
+A log module which supports simple level configurations and color titles. 
+
+## Parameters
+
+- `$log_level` : The accepted values are `"OFF"` (-1), `"INFO"` (20), 
+   `"WARNING"` (30), `"ERROR"` (40) or positive integers. The default value is `"INFO"`.
+- `level` : The accepted values are `"OFF"` (-1), `"INFO"` (20), 
+   `"WARNING"` (30), `"ERROR"` (40) or positive integers. If the value is greater or equal to `$log_level`, the `echo` message will display in the console.
+- `level_color` : Controls the color of level title. It accepts the same values as the CSS `color` property. 
+
+## Examples
+
+	include <log.scad>;
+	
+	log() 
+	    echo("    INFO message");
+	    
+	log("WARNING")
+	    echo("    WARNING message"); 
+	
+	log("ERROR") {
+	    echo("    ERROR message 1"); 
+	    echo("    ERROR message 2"); 
+	}
+
+![log](images/lib-log-1.JPG)
+
+	include <log.scad>;
+	
+	$log_level = "WARNING";
+	
+	log() 
+	    echo("    INFO message");
+	    
+	log("WARNING", "purple")
+	    echo("    WARNING message"); 
+	
+	log("ERROR", "rgb(255, 100, 100)") {
+	    echo("    ERROR message 1"); 
+	    echo("    ERROR message 2"); 
+	}
+
+![log](images/lib-log-2.JPG)
+