Fix small spelling error (#184)

src/components/InteractiveTutorial/MdxPages/Index.mdx

@@ -8,7 +8,7 @@ All the examples in this tutorial do not require any additional setup from your
 This tutorial will demonstrate principles of Qdrant API, which you would be able to reproduce in 
 Qdrant UI or in Qdrant client for your [favorite programming language](https://qdrant.tech/documentation/interfaces/).
 
-## What is a interactive tutorial?
+## What is an interactive tutorial?
 
 In this tutorial, we will guide you through Qdrant API step by step.
 You will explore the main features and learn core concepts of Qdrant on an interactive examples.