Add prerequisite for this 401 errors

What does this MR do and why?

Closes #32 (closed)

Extend the error message with more details explaining to double check Duo Pro subscription and permissions for a user. Additionally, provide a link to the documentation page.

internal/aiclient/gitlab_test.go

@@ -5,7 +5,6 @@ import (
 	"net/http/httptest"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"gitlab.com/gitlab-com/create-stage/code-creation/repository-x-ray/internal/deps"
 )
@@ -20,13 +19,13 @@ func Test_apiEndpoint(t *testing.T) {
 
 func TestGitLabCompletions(t *testing.T) {
 	tests := []struct {
-		name           string
-		status         int
-		resp           string
-		want           []deps.Dependency
-		wantErr        bool
-		expectedErrMsg string
-		requestCount   int
+		name         string
+		status       int
+		resp         string
+		want         []deps.Dependency
+		wantErr      bool
+		wantErrMsg   string
+		requestCount int
 	}{
 		{
 			"success",
@@ -92,10 +91,9 @@ func TestGitLabCompletions(t *testing.T) {
 
 			got, err := gl.Completions("prompt")
 			if tt.wantErr {
-				// test error thrown
 				require.Error(t, err)
 				// test error message
-				assert.EqualError(t, err, tt.expectedErrMsg)
+				require.EqualError(t, err, tt.wantErrMsg)
 			} else {
 				// reports will be generated
 				require.NoError(t, err)