Add support for unifi_network datasource

#168

docs/data-sources/network.md

@@ -0,0 +1,27 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "unifi_network Data Source - terraform-provider-unifi"
+subcategory: ""
+description: |-
+  unifi_network data source can be used to retrieve the ID for a network by name.
+---
+
+# unifi_network (Data Source)
+
+`unifi_network` data source can be used to retrieve the ID for a network by name.
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Optional
+
+- **name** (String) The name of the user group to look up. Defaults to `Default`.
+- **site** (String) The name of the site the user group is associated with.
+
+### Read-Only
+
+- **id** (String) The ID of this AP group.
+
+