Flesh out README with initial usage docs (#9)

Signed-off-by: Yoriyasu Yano <430092+yorinasub17@users.noreply.github.com>

CONTRIBUTING.md

@@ -0,0 +1,32 @@
+# How to contribute to tf.libsonnet
+
+**Filing issues**
+
+- **Report bugs and feature requests on the libgenerator repository as GitHub issues**. This is an autogenerated
+  library, which means that any bugs and feature requests need to be reported on the [libgenerator
+  project](https://github.com/tf-libsonnet/libgenerator) which is responsible for generating this repository. If you
+  found an issue, you can open a new issue from [this
+  link](https://github.com/tf-libsonnet/libgenerator/issues/new/choose).
+- **Do not open a GitHub issue if you are reporting a security vulnerability with the tf.libsonnet project**. Instead,
+  refer to our [security policy](/SECURITY.md).
+
+
+**Contributing a change**
+
+- **This is an autogenerated library**. This means that all contributions will not be merged until the changes can be
+  autogenerated from the generator. You may still open a Pull Request with a suggested change, especially if it helps
+  augment an issue description by providing an example of what should be generated.
+- **All commits must be signed off to adhere to the Developer Certificate of Origin (DCO)**. If you are contributing a
+  change to `libgenerator`, note that the `tf.libsonnet` org requires all contributors to sign off on [the
+  DCO](https://developercertificate.org/). You can do this with the `-s` flag when making commits with `git commit`.
+    - If you forgot to sign off on any commits in a Pull Request, you can amend the offending commit with `git commit -s
+      --amend`.
+- **All commits must be signed**. The `tf.libsonnet` org requires all contributors to [sign their
+  commits](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits). If you do
+  not wish to maintain a set of private keys on your account, you can also use the
+  [sigstore/gitsign](https://github.com/sigstore/gitsign) project for keyless signing with your GitHub account.
+
+**Support**
+
+- Ask any question about how to use the `tf.libsonnet` libraries in the [Organization
+  GitHub Discussion](https://github.com/orgs/tf-libsonnet/discussions).

README.md

@@ -23,3 +23,84 @@ This repository contains [Jsonnet](https://jsonnet.org/) functions for generatin
 >
 > If you would like to contribute a change, you may open a Pull Request with a suggested change, but please note that it
 > will **not be merged in until the necessary updates have been made to the generator**.
+
+## Usage
+
+Install the package using [jsonnet-bundler](https://github.com/jsonnet-bundler/jsonnet-bundler):
+
+```
+jb install github.com/tf-libsonnet/hashicorp-azuread@main
+
+# Or if you want to install a specific release
+#   jb install github.com/tf-libsonnet/hashicorp-azuread@v0.0.1
+# Or if you want to install bindings for a specific provider major version series
+#   jb install github.com/tf-libsonnet/hashicorp-azuread/2.x@main
+```
+
+You can then import the package in your Jsonnet code:
+
+```jsonnet
+// main.tf.json.jsonnet
+local azuread = import 'github.com/tf-libsonnet/hashicorp-azuread/main.libsonnet';
+
+local tid = '00000000-0000-0000-0000-000000000000';
+
+local o =
+  azuread.data.client_config.new('current')
+  + azuread.group.new(
+    'example',
+    display_name='example',
+    owners=[o._ref.data.azuread_client_config.current.get('object_id')],
+    security_enabled=true,
+  );
+
+azuread.provider.new(tenant_id=tid, src='hashicorp/azuread')
++ o
+```
+
+This will generate the following Terraform JSON :
+
+```json
+{
+   "data": {
+      "azuread_client_config": {
+         "current": { }
+      }
+   },
+   "provider": {
+      "azuread": [
+         {
+            "tenant_id": "00000000-0000-0000-0000-000000000000"
+         }
+      ]
+   },
+   "resource": {
+      "azuread_group": {
+         "example": {
+            "display_name": "example",
+            "owners": [
+               "${data.azuread_client_config.current.object_id}"
+            ],
+            "security_enabled": true
+         }
+      }
+   },
+   "terraform": {
+      "required_providers": {
+         "azuread": {
+            "source": "hashicorp/azuread"
+         }
+      }
+   }
+}
+```
+
+Refer to the [reference docs](/docs/2.x/README.md) for a list of supported data sources and resources:
+
+- [provider config](/docs/2.x/provider.md)
+- [resources](/docs/2.x/README.md)
+- [data sources](/docs/2.x/data/index.md)
+
+## Contributing
+
+Refer to the [CONTRIBUTING.md](/CONTRIBUTING.md) document for information on how to contribute to `tf.libsonnet`.