Add some Terraform to describe the dynamodb table

Fixes #2

README.md

@@ -1,5 +1,4 @@
-dynamodb lock
-=============
+# dynamodb lock
 
 Dynamodb based distributed lock implemented in pure Rust. The design is largely
 inspired by
@@ -10,8 +9,7 @@ implement PUT if absence semantic for concurrent S3 writes. It is considered
 production ready and battle tested through the
 [kafka-delta-ingest](https://github.com/delta-io/kafka-delta-ingest) project.
 
-Usage
------
+## Usage
 
 ```rust
 let region = dynamodb_lock::Region::default();
@@ -32,3 +30,38 @@ lock_client.release_lock(&lock).await?;
 
 For real world example, see
 https://github.com/delta-io/delta-rs/blob/main/rust/src/storage/s3/mod.rs.
+
+## Deployment
+
+Using the DynamoDb lock requires a DynamoDb table to have already been created
+in AWS. The following Terraform code is an example which will create table
+named "lock_example",.
+
+
+```terraform
+resource "aws_dynamodb_table" "oxbow_locking" {
+  name         = "lock_example"
+  billing_mode = "PROVISIONED"
+  # Default name of the partition key hard-coded in delta-rs
+  hash_key       = "key"
+  read_capacity  = 10
+  write_capacity = 10
+
+  attribute {
+    name = "key"
+    type = "S"
+  }
+  # The leaseDuration is used by dynamodb-lock-rs and *must* be a Number type
+  attribute {
+    name = "leaseDuration"
+    type = "N"
+  }
+  ttl {
+    attribute_name = "leaseDuration"
+    enabled        = true
+  }
+}
+```
+
+The locking code should then be configured with the environment variable
+`DYNAMO_LOCK_TABLE_NAME` set to "lock_example"