chore: add documentation

Author: jim80net

README.md

@@ -1,2 +1,56 @@
 # terraform_elasticache_slowlog_to_datadog
-Deploy Elasticache Slowlog to Datadog lambda function to AWS account
+
+**Deploy Elasticache Slowlog to Datadog lambda function to AWS account**
+
+This terraform module deploys [elasticache-slowlog-to-datadog](https://github.com/scribd/elasticache-slowlog-to-datadog)
+to AWS to submit Elasticache slowlog entries. 
+
+[![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)
+
+# Usage
+
+```
+module slowlog_check {
+  source                      = "git::https://github.com/scribd/terraform-elasticache-slowlog-to-datadog.git?ref=master"
+  elasticache_endpoint        = "master.replicationgroup.abcdef.use2.cache.amazonaws.com"
+  elasticache_security_groups = ["sg-12345"]
+  subnet_ids                  = [ "subnet-0123456789abcdef", "subnet-abcdef1234567890", "subnet-1234567890abcdef", ]
+  vpc_id                      = "vpc-0123456789abcdef"
+  datadog_api_key             = "abc123"
+  datadog_app_key             = "abc123"
+  namespace                   = "example"
+  env                         = "dev"
+  tags                        = {"foo" = "bar"}
+}
+```
+
+## Parameters
+
+The following parameters need to be supplied to the terraform job
+
+Parameter                   | Type         | Description                                                                  | Required | Default
+----------------------------|--------------|------------------------------------------------------------------------------|----------|---------
+elasticache_endpoint        | string       | AWS Elasticache endpoint to get slowqueries from                             | yes      | -
+elasticache_security_groups | list(string) | AWS Elasticache Security groups to bind to                                   | yes      | []
+subnet_ids                  | list(string) | Subnets to associate with VPC lambda job                                     | yes      | -
+vpc_id                      | string       | VPC to associate with VPC lambda job                                         | yes      | -
+datadog_api_key             | string       | Datadog API key                                                              | yes      | -
+datadog_app_key             | string       | Datadog App key                                                              | yes      | -
+namespace                   | string       | Namespace tag to pass to datadog                                             | yes      | -
+env                         | string       | Namespace tag to pass to datadog                                             | yes      | -
+metric_name                 | string       | Custom metric name to pass ot datadog                                        | no       | "elasticache.slowlog"
+ssm_path                    | string       | Custom SSM path to provision Datadog access ID's in. Leading slash ommitted. | no       | "slowlog_check"
+tags                        | object       | Additional tags to create resources with and to send to datadog              | no       | {}
+
+# Requirements
+
+To use *terraform-elasticache-slowlog-to-datadog* you need:
+
+- An AWS account with an Elasticache instance running the `redis5.0` engine.
+- A Datadog account
+
+# Development
+
+Releases are cut using [semantic-release](https://github.com/semantic-release/semantic-release).
+
+Please write commit messages following [Angular commit guidelines](https://github.com/angular/angular.js/blob/master/DEVELOPERS.md#-git-commit-guidelines)