Update README.md

Adding links about custom runtimes

Author: MFernstrom

README.md

@@ -7,3 +7,9 @@ The custom runtime allows you to use FreePascal natively on AWS Lambda without a
 This is the core skeleton and contains no functionality other than the basic setup and event polling.
 
 Use it as-is for max performance, or wait for the webserver one (Coming soon) which lets you easily use fpHttpServer (Equivalent to using Express.js with the Node.js runtime)
+
+### Useful links
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+https://docs.aws.amazon.com/lambda/latest/dg/runtimes-custom.html
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+https://docs.aws.amazon.com/lambda/latest/dg/runtimes-walkthrough.html