Readme: add documentation.
# Terraform Aiven
Terraform provider resources for Aiven.
+
+## Provider
+
+Set up the provider with your own API Key. You can get this by using the [Aiven Client](https://github.com/aiven/aiven-client).
+
+```
+provider "aiven" {
+ api_key = "<API_KEY>"
+}
+```
+
+## Resource Project
+
+**Note**: it is currently not possible to automatically set up a new card for a project. If you already have a card linked to your account, you can get the card id and use it to set up this project.
+
+```
+resource "aiven_service" "my-project" {
+ project = "<PROJECT_NAME>"
+ card_id = "<CARD_ID>"
+ cloud = "google-europe-west1"
+}
+```
+
+## Resource Service
+
+**Note**: to make a new service, you'll have to have set up a project with a valid billing plan.
+
+```
+resource "aiven_service" "my-service" {
+ project = "<PROJECT_NAME>"
+ group_name = "my-group"
+ cloud = "google-europe-west1"
+ plan = "business-16"
+ service_name = "<SERVICE_NAME>"
+ service_type = "pg"
+}
+```
