Documentation update of external_apis.adoc#example-scala-code

Update the Example Scala Code in the Reference Guide as it contains deprecated content such as

• new HBaseConfiguration()
• new HTable(conf, "mytable")
• add(Bytes.toBytes("ids"),Bytes.toBytes("id1"),Bytes.toBytes("one"))

Replace it with:

• HBaseConfiguration.create()
• TableName.valueOf("mytable")
• addColumn(Bytes.toBytes("ids"),Bytes.toBytes("id1"),Bytes.toBytes("one"))