reuse: remove glob for markdown files

Instead, place the copyright and license right into the source.

To satisfy reuse, this also removes the unnecessary MIT.txt
symlinks.

docs/tutorial/cpp/src/SUMMARY.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Summary
 
 - [Introduction](./introduction.md)

docs/tutorial/cpp/src/conclusion.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Conclusion
 
 In this tutorial, we have demonstrated how to combine some built-in Slint elements with C++ code to build a little

docs/tutorial/cpp/src/creating_the_tiles_from_cpp.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Creating The Tiles From C++
 
 What we'll do is take the list of tiles declared in the .slint language, duplicate it, and shuffle it.

docs/tutorial/cpp/src/from_one_to_multiple_tiles.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # From One To Multiple Tiles
 
 After modeling a single tile, let's create a grid of them. For the grid to be our game board, we need two features:

docs/tutorial/cpp/src/game_logic_in_cpp.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Game Logic In C++
 
 We'll implement the rules of the game in C++ as well. The general philosophy of Slint is that merely the user

docs/tutorial/cpp/src/getting_started.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Getting Started
 
 In this tutorial, we use C++ as the host programming language. We also support other programming languages like

docs/tutorial/cpp/src/ideas_for_the_reader.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Ideas For The Reader
 
 The game is visually a little bare. Here are some ideas how you could make further changes to enhance it:

docs/tutorial/cpp/src/introduction.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Introduction
 
 This tutorial will introduce you to the Slint UI framework in a playful way by implementing a little memory game. We're going to combine the `.slint` language for the graphics with the game rules implemented in C++.

docs/tutorial/cpp/src/memory_tile.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Memory Tile
 
 With the skeleton in place, let's look at the first element of the game, the memory tile. It will be the

docs/tutorial/cpp/src/polishing_the_tile.md

@@ -1,3 +1,4 @@
+<!-- Copyright © SixtyFPS GmbH <info@slint.dev> ; SPDX-License-Identifier: MIT -->
 # Polishing the Tile
 
 Next, let's add a curtain like cover that opens up when clicking. We achieve this by declaring two rectangles