docs: added comments

auth.go

@@ -11,11 +11,16 @@ import (
 )
 
 var (
+	// CognitoClient is the client that interacts with Cognito.
 	CognitoClient           *cognitoidentityprovider.Client
+	// CognitoUserPoolID is the id of the user pool in Cognito.
 	CognitoUserPoolID       string
+	// CognitoUserPoolClientID is the id of the user pool client in Cognito.
 	CognitoUserPoolClientID string
 )
 
+// Initialize will initialize the auth package. Both profile and region parameters are option if authentication can be
+// achieved via another method. For example, environment variables or IAM roles.
 func Initialize(ctx context.Context, profile string, region string, cognitoUserPoolID string, cognitoClientID string) error {
 	var cfg aws.Config
 	var err error

sign_in.go

@@ -9,6 +9,7 @@ import (
 	"github.com/gofor-little/xerror"
 )
 
+// SignIn will attempt to sign a user in, returning the result.
 func SignIn(ctx context.Context, emailAddress string, password string) (*types.AuthenticationResultType, error) {
 	if err := checkPackage(); err != nil {
 		return nil, xerror.Wrap("checkPackage call failed", err)