Add custom intro page by fetching markdown content from a file (#697)

Signed-off-by: Tilman Vatteroth <tilman.vatteroth@tu-dortmund.de>

src/components/intro-page/requests.ts

@@ -0,0 +1,17 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { defaultFetchConfig, expectResponseCode } from '../../api/utils'
+
+export const getFrontPageContent = async (baseUrl: string): Promise<string> => {
+  const response = await fetch(baseUrl + '/intro.md', {
+    ...defaultFetchConfig,
+    method: 'GET'
+  })
+  expectResponseCode(response)
+
+  return await response.text()
+}