Added instance configuration support

src/utils/slices/instances/updateConfiguration.ts

@@ -0,0 +1,12 @@
+import apiInstance from '@api/instance'
+import { createAsyncThunk } from '@reduxjs/toolkit'
+
+export const updateConfiguration = createAsyncThunk(
+  'instances/updateConfiguration',
+  async (): Promise<Mastodon.Instance> => {
+    return apiInstance<Mastodon.Instance>({
+      method: 'get',
+      url: `instance`
+    }).then(res => res.body)
+  }
+)