fix all type errors

interfaces/IDocProps.ts

@@ -0,0 +1,15 @@
+export interface IDocProps {
+  template: string
+  subject: string
+  body: string
+  address: string
+  date?: string
+  opening?: string
+  closing?: string
+  yourRef?: string
+  yourMail?: string
+  myRef?: string
+  customer?: string
+  invoice?: string
+  specialMail?: string
+}