Janitor: Fix warnings about markdown files

These might change the layout of the rendered markdown files. This will
also fix some typos along the way:-)

docs/tutorial/rust/src/memory_tile.md

@@ -4,7 +4,7 @@ With the skeleton in place, let's look at the first element of the game, the mem
 visual building block that consists of an underlying filled rectangle background, the icon image. Later we'll add a
 covering rectangle that acts as a curtain. The background rectangle is declared to be 64 logical pixels wide and tall,
 and it is filled with a soothing tone of blue. Note how lengths in the `.60` language have a unit, here
-the `px` suffix. That makes the code easier to read and the compiler can detect when your're accidentally
+the `px` suffix. That makes the code easier to read and the compiler can detect when your are accidentally
 mixing values with different units attached to them.
 
 We copy the following code inside of the `sixtyfps!` macro:
@@ -28,5 +28,5 @@ This should unpack an `icons` directory containing a bunch of icons.
 
 Running the program with `cargo run` gives us a window on the screen that shows the icon of a bus on a
 blue background.
-    
+
 ![Screenshot of the first tile](https://sixtyfps.io/blog/memory-game-tutorial/memory-tile.png "Memory Tile Screenshot")