chore: Match licensing with other plugins

plugins/single-instance/LICENSE.spdx

@@ -0,0 +1,20 @@
+SPDXVersion: SPDX-2.1
+DataLicense: CC0-1.0
+PackageName: tauri
+DataFormat: SPDXRef-1
+PackageSupplier: Organization: The Tauri Programme in the Commons Conservancy
+PackageHomePage: https://tauri.app
+PackageLicenseDeclared: Apache-2.0
+PackageLicenseDeclared: MIT
+PackageCopyrightText: 2019-2022, The Tauri Programme in the Commons Conservancy
+PackageSummary: <text>Tauri is a rust project that enables developers to make secure
+and small desktop applications using a web frontend.
+                </text>
+PackageComment: <text>The package includes the following libraries; see
+Relationship information.
+                </text>
+Created: 2019-05-20T09:00:00Z
+PackageDownloadLocation: git://github.com/tauri-apps/tauri
+PackageDownloadLocation: git+https://github.com/tauri-apps/tauri.git
+PackageDownloadLocation: git+ssh://github.com/tauri-apps/tauri.git
+Creator: Person: Daniel Thompson-Yvetot

plugins/single-instance/LICENSE_MIT

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2017 - Present Tauri Programme within The Commons Conservancy
+Copyright (c) 2017 - Present The Tauri Programme in the Commons Conservancy
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal