Feat: Add a README file to the root backup directory

src/Backup.ts

@@ -477,6 +477,7 @@ class Backup {
         await this.backupNotebooks();
 
         const backupDst = await this.makeBackupSet();
+        await this.writeReadme(backupDst);
 
         await joplin.settings.setValue(
           "lastBackup",
@@ -684,6 +685,16 @@ class Backup {
     }
   }
 
+  private async writeReadme(backupFolder: string) {
+    const readmePath = path.join(backupFolder, "README.md");
+    this.log.info("writeReadme to", readmePath);
+    const readmeText = i18n.__(
+      "backupReadme",
+      this.backupStartTime.toLocaleString()
+    );
+    await fs.writeFile(readmePath, readmeText, "utf8");
+  }
+
   private async backupNotebooks() {
     const notebooks = await this.selectNotebooks();
 

src/locales/en_US.json

@@ -86,6 +86,7 @@
       "description": "Execute command when backup is finished"
     }
   },
+  "backupReadme": "# Joplin Backup\n\nThe backups in this folder were created with the Simple Backup plugin for Joplin. The most recent backup was created on %s.\n\nSee the [Simple Backup documentation](https://joplinapp.org/plugins/plugin/io.github.jackgruber.backup/#restore) for information about how to restore from this backup.",
   "command": {
     "createBackup": "Create backup"
   }