Fix typo

Author: Ronald Scott

Auth/2_ServerlessAPI/Optional-APIGateway-IAMAuth.md

@@ -8,7 +8,7 @@ In this **optional extension to module 2**, you will update your serverless back
 
 Building on Module 2, this module updates our Serverless backend built earlier using Amazon API Gateway and AWS Lambda to use IAM-based authorization. This extends our authorization capability to offer fine-grained access control authorizing differently per API operation and enhancing security via request signing. By enabling IAM-based authorization, you will use the same type of authentication, authorization, and request signing used by all AWS services and SDKs.
 
-[Request signing](https://docs.aws.amazon.com/general/latest/gr/signing_aws_api_requests.html) is a more secure implementation of API request authentication where each API request made is signed with a signature unique to the request itself. Hence, no static API keys or bearer tokens are directly sent to the backend service and any man-in-the-middle attacks would not be able to use such API keys or bearer tokens to impersonate a valid user with the backend resources. AWS APIs and SDKs use a request signing algorithm nammed [Signature V4 (Sigv4)](https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html) which is what you will enable your API to use in this module.
+[Request signing](https://docs.aws.amazon.com/general/latest/gr/signing_aws_api_requests.html) is a more secure implementation of API request authentication where each API request made is signed with a signature unique to the request itself. Hence, no static API keys or bearer tokens are directly sent to the backend service and any man-in-the-middle attacks would not be able to use such API keys or bearer tokens to impersonate a valid user with the backend resources. AWS APIs and SDKs use a request signing algorithm named [Signature V4 (Sigv4)](https://docs.aws.amazon.com/general/latest/gr/signature-version-4.html) which is what you will enable your API to use in this module.
 
 > For production APIs, you should use either the token-based authorization OR request signing authorization via IAM demonstrated in this module, but not use both for the same API.