DOC: updated doc about creating lambda layer

lambda/dns-query/README.md

@@ -1,5 +1,33 @@
 # Steps to create a lambda python package
 
-pip install dnspython -t ./
-touch lambda_function.py
-zip -r dist.zip .
+## Create layer
+cd layers
+pip install dnspython -t python/lib/python3.12/site-packages/
+
+Then in terraform, create an archive for the layer
+```hcl
+data "archive_file" "dnspython" {
+  source_dir  = "layers"
+  type        = "zip"
+  output_path = "layer-dnspython.zip"
+}
+
+resource "aws_lambda_layer_version" "dnspython" {
+  description = "Python3 DnsPython library"
+  depends_on  = [data.archive_file.layer1]
+  filename    = "layer-dnspython.zip"
+  layer_name  = "Python3DnsLibrary"
+  license_info             = "ISCL"
+  compatible_architectures = ["arm64", "x86_64"]
+  compatible_runtimes = ["python3.12"]
+}
+
+# In the lambda function, reference the layer
+resource "aws_lambda_function" "myFunction" {
+  ...
+  layers           = [aws_lambda_layer_version.libraries.arn]
+}
+
+```
+
+