Squashed commit of the following:

commit 739f9c349031510e8ef010ba2445a2a1fdbec247
Author: Simon Cambier <simon.cambier@protonmail.com>
Date:   Sun Oct 16 16:57:03 2022 +0200

    Code cleaning + README

commit 85762bae592f3eafd34ba22b0cf1841bfbd91ca6
Author: Simon Cambier <simon.cambier@protonmail.com>
Date:   Sun Oct 16 14:59:01 2022 +0200

    Cleaning deleted PDFs from cache

commit 1a37bf38d3f64870d4b40df1b67d8106c893ab64
Author: Simon Cambier <simon.cambier@protonmail.com>
Date:   Sun Oct 16 13:18:06 2022 +0200

    PDF cache saved to IndexedDB

src/typings/types-obsidian.d.ts

@@ -19,6 +19,10 @@ declare module 'obsidian' {
   interface Vault {
     getConfig(string): unknown
   }
+
+  interface App {
+    appId: string
+  }
 }