add data source unifi_user

implements #174

docs/data-sources/user.md

@@ -0,0 +1,45 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "unifi_user Data Source - terraform-provider-unifi"
+subcategory: ""
+description: |-
+  unifi_user retrieves properties of a user (or "client" in the UI) of the network by MAC address.
+---
+
+# unifi_user (Data Source)
+
+`unifi_user` retrieves properties of a user (or "client" in the UI) of the network by MAC address.
+
+## Example Usage
+
+```terraform
+data "unifi_user" "client" {
+  mac = "01:23:45:67:89:ab"
+}
+```
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- **mac** (String) The MAC address of the user.
+
+### Optional
+
+- **site** (String) The name of the site the user is associated with.
+
+### Read-Only
+
+- **blocked** (Boolean) Specifies whether this user should be blocked from the network.
+- **dev_id_override** (Number) Override the device fingerprint.
+- **fixed_ip** (String) fixed IPv4 address set for this user.
+- **hostname** (String) The hostname of the user.
+- **id** (String) The ID of the user.
+- **ip** (String) The IP address of the user.
+- **name** (String) The name of the user.
+- **network_id** (String) The network ID for this user.
+- **note** (String) A note with additional information for the user.
+- **user_group_id** (String) The user group ID for the user.
+
+