Update docs with TLS configurations (#376)

Author: lahsivjar

docs/monitoring-aws-lambda.asciidoc

@@ -139,6 +139,34 @@ preview:[]
 Starting in Elastic Stack version 8.5.0, the Elastic APM lambda extension supports the collection of log events by default.
 Log events can be viewed in {kib} in the APM UI. Disable log collection by setting this to `false`.
 
+[float]
+=== `ELASTIC_APM_LAMBDA_VERIFY_SERVER_CERT`
+
+[small]#Added in: v1.3.0.
+
+Whether to enable {apm-lambda-ext} to verify APM Server's certificate chain and host name.
+
+[float]
+=== `ELASTIC_APM_LAMBDA_SERVER_CA_CERT_PEM`
+
+[small]#Added in: v1.3.0.
+
+The certificate passed as environment variable. To be used to verify APM Server's certificate chain if verify server certificate is enabled.
+
+[float]
+=== `ELASTIC_APM_SERVER_CA_CERT_FILE`
+
+[small]#Added in: v1.3.0.
+
+The certificate passed as a file name available to the extension. To be used to verify APM Server's certificate chain if verify server certificate is enabled.
+
+[float]
+=== `ELASTIC_APM_SERVER_CA_CERT_ACM_ID`
+
+[small]#Added in: v1.3.0.
+
+The ARN for Amazon-issued certificate. To be used to verify APM Server's certificate chain if verify server certificate is enabled.
+
 [NOTE]
 ====
 You may see errors similar to the following in {stack} versions less than 8.5: