add documentation

Author: kingzbauer

README.md

@@ -18,5 +18,6 @@ Installation
 
 You can use the different service packages by importing them
 
-`go
-import "github.com/kingzbauer/africastalking-go`
+```go
+import "github.com/kingzbauer/africastalking-go/sms"
+```

client/doc.go

@@ -0,0 +1,12 @@
+/*
+Package client implements the underlying API calling logic.
+
+Initialize the `Client` and pass it to other API services.
+
+Example:
+
+	cli := New(apiKey, username, sandbox)
+	// You can pass this to the service methods
+	rep, err := SendMessage(cli, req)
+*/
+package client

doc.go

@@ -0,0 +1,8 @@
+/*
+Package africastalking is an unofficial AfricasTalking SDK providing SMS, Voice, Payment, Airtime, USSD API implementations
+
+Currently implemented services
+
+		- SMS
+*/
+package africastalking

sms/doc.go

@@ -0,0 +1,35 @@
+/*
+Package sms provides SMS sending and fetching API
+
+Example Send SMS:
+
+	package main
+
+	import (
+		"fmt"
+		"os"
+
+		"github.com/kingzbauer/africastalking-go/sms"
+	)
+
+	var (
+		apiKey string = "yourapikey"
+		username string = "yourusername"
+		shortCode string = "yourshortcode"
+		live bool = true
+		number = "+2547********"
+	)
+
+	func main() {
+		srv := sms.NewService(apiKey, username, shortCode, live)
+		rep, err := srv.Send("Test message", []string{number}, shortCode)
+
+		if err != nil {
+			fmt.Printf("Error: %s\n", err)
+			os.Exit(1)
+		}
+
+		fmt.Printf("Response: %s\n", rep)
+	}
+*/
+package sms