Add new configuration document for connection vault (#122)

docs/reference/config-files/connection/vault.md

@@ -0,0 +1,41 @@
+---
+title: vault
+sidebar_label: vault
+---
+
+# vault
+
+The `vault` connection can be used to access Vault resources.
+
+```hcl
+connection "vault" "my_vault" {
+  address = "http://127.0.0.1:8200"
+  token = "hvs.FaKe"
+}
+```
+
+## Arguments
+
+| Name      | Type   | Required? | Description          |
+| --------- | ------ | --------- | -------------------- |
+| `address` | String | Optional  | Vault server address |
+| `token`   | String | Optional  | API token            |
+
+All arguments are optional, and a `vault` connection with no arguments will behave the same as the [default connection](#default-connection).
+
+## Attributes (Read-Only)
+
+| Attribute | Type | Description                                                                                  |
+| --------- | ---- | -------------------------------------------------------------------------------------------- |
+| `env`     | Map  | A map of the resolved connection-related environment variables (`VAULT_ADDR`, `VAULT_TOKEN`) |
+
+## Default Connection
+
+The `vault` connection type includes an implicit, default connection (`connection.vault.default`) that will be configured to set the `token` to the `VAULT_TOKEN` environment variable and the `domain` to `VAULT_ADDR`.
+
+```hcl
+connection "vault" "default" {
+  domain = env("VAULT_ADDR")
+  token  = env("VAULT_TOKEN")
+}
+```