added serial docs

libs/microbit/serial.ts

@@ -7,30 +7,24 @@ namespace serial {
      * Prints a line of text to the serial
      * @param value to send over serial
      */
+    //% help=/reference/serial/write-line
     //% blockId=serial_writeline block="serial|write %text"
     export function writeLine(text: string): void {
         writeString(text);
         writeString("\r\n");
     }
 
-    /**
-     * Prints a numeric value to the serial
-     */
-    export function writeNumber(value: number): void {
-        writeString(value.toString());
-    }
-
     /**
      * Writes a ``name: value`` pair line to the serial.
      * @param name name of the value stream, eg: x
      * @param value to write
      */
+    //% help=/reference/serial/write-value
     //% weight=80
     //% blockId=serial_writevalue block="serial|write %name|= %value"
     export function writeValue(name: string, value: number): void {
         writeString(name);
-        writeString(": ");
-        writeNumber(value);
-        writeLine("");
+        writeString(":");
+        writeLine(value.toString());
     }
 }