docs: add Ampli SDK reference (#162)

README.md

@@ -10,6 +10,9 @@
 # Official Amplitude SDK for Node.js
 This is Amplitude Node.js SDK written in Typescript, the 1st backend SDK for Amplitude. At this moment, we keep it minimal and simple because we want to give more thoughts over different customers' needs. Modularization and flexiblity will be the main priorities for this SDK. We would like to hear your ideas as well on how you plan on using this library!
 
+## Amplitude and Ampli SDK
+[Ampli SDK](https://developers.data.amplitude.com/ampli-sdk-overview/) is autogenerated library based on your pre-defined [tracking plan](https://developers.data.amplitude.com/what-is-a-tracking-plan). The Ampli SDK, is a lightweight wrapper over the Amplitude SDK that provides type-safety, supports linting, and enables features like input validation. The code replicates the spec in the Tracking Plan and enforces its rules and requirements. This repository is about **Amplitude SDK**. To learn more about Ampli SDK, please refer to the [Ampli Node](https://developers.data.amplitude.com/nodejs-ampli) and [examples](https://github.com/amplitude/ampli-examples).
+
 ## Installation and Quick Start
 Please visit our :100:[Developer Center](https://developers.amplitude.com/docs/nodejs) for instructions on installing and using our the SDK.