📝 Update README

Author: hreeder

README.md

@@ -0,0 +1,43 @@
+# ƛ GitHub Security Updater
+
+This is a Lambda to periodically synchronize security groups with the IP ranges for webhooks provided by GitHub's API.
+
+The use case for this would be having a service locked down by source IP in the whitelist, which still needs to receive webhooks for repository events from GitHub (ie a CI/CD tool).
+
+This tool uses the [Serverless Framework](https://serverless.com/) for deployment
+
+## How it works
+
+This will take 
+
+## Configuration, Installation & Deployment
+
+Clone this repository, and change to the cloned directory.
+
+Configuration is expected to be found in AWS EC2 Systems Manager Parameter Store.
+
+All variables live under the prefix of `/github_secgrp_updater/{STAGE}`. Replace stage with the relevant stage you are deploying (ie `/github_secgrp_updater/dev/`)
+
+Relevant variables are shown in the table below.
+
+|----------------------|----------|---------------------|-------------|
+| Variable             | Required | Default Value       | Description |
+| /vpc_ids             | Yes      |                     | A comma separated list of VPC IDs in which to maintain a security group. |
+| /secgrp_name         | No       | AllowGitHubWebhooks | Override the name of the maintained security group |
+|----------------------|----------|---------------------|-------------|
+
+
+Finally, deploy with the following
+
+```
+npm install serverless -g
+
+serverless deploy
+```
+
+### Deploying multiple environments
+
+This supports the serverless framework's concept of stages. Deploy additional stages like so:
+```
+serverless deploy --stage prod
+```