Add new configuration document for connection clickup (#99)

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

@@ -0,0 +1,32 @@
+---
+title:  clickup
+sidebar_label: clickup
+---
+
+# clickup
+
+The `clickup` connection can be used to access ClickUp resources.
+
+```hcl
+connection "clickup" "my_clickup" {
+  token = "pk_616_L5H36X3CXXXXXXXWEAZZF0NM5"
+}
+```
+
+## Arguments
+
+| Name            | Type    | Required?| Description
+|-----------------|---------|----------|-------------------
+| `token`         |  String | Optional | API token
+
+All arguments are optional, and a `clickup` connection with no arguments will behave the same as the [default connection](#default-connection).
+
+## Default Connection
+
+The `clickup` connection type includes an implicit, default connection (`connection.clickup.default`) that will be configured to set the `token` to the `CLICKUP_TOKEN` environment variable.
+
+```hcl
+connection "clickup" "default" {
+  token = env("CLICKUP_TOKEN")
+}
+```