fix(core): Fix file import paths and remove markdown syntax from README

test/assets/getasset.ts

@@ -0,0 +1,22 @@
+import * as smartfile from '@push.rocks/smartfile';
+
+export async function getInvoice(filePath: string): Promise<Buffer> {
+  const file = await smartfile.fs.toBuffer('./test/assets/corpus/' + filePath);
+  return file;
+}
+
+export const invoices = {
+  ZUGFeRDv2: {
+    correct: {
+      intarsys: {
+        BASIC: {
+          'zugferd_2p0_BASIC_Einfach.pdf': 'ZUGFeRDv2/correct/intarsys/BASIC/zugferd_2p0_BASIC_Einfach.pdf'
+        }
+      }
+    }
+  }
+}
+
+export const letterObjects = {
+  letter1: await import('./letter/letter1.js'),
+}