docs: Fix broken image link on flame_tiled pub (#2407)

Fix broken image link on flame_tiled pub.
Sadly the repo relative link works on GitHub but not on pub.
This replaces it with an equivalent githubusercontent URL.
This is how it is done by other packages and recommended on Stack Overflow according to my research (but open to other better solutions).

image

I also made the image a bit bigger bc it was small and hard to see (to me).

packages/flame_tiled/README.md

@@ -30,10 +30,10 @@ Adds support for <a href="https://www.mapeditor.org/">Tiled</a>'s tile maps to y
 Package to bridge the `tiled` library into easy-to-use Flame components.
 
 <p align="center">
-    <img alt="flame_tiled example" width="200px" src="/packages/flame_tiled/example/screenshot.png">
+    <img alt="flame_tiled example" width="500px" src="https://raw.githubusercontent.com/flame-engine/flame/master/packages/flame_tiled/example/screenshot.png">
 </p>
 
-More [here](https://docs.flame-engine.org/main/tiled.html).
+More documentation can be found [here](https://docs.flame-engine.org/main/tiled.html).
 
 
 ## Contributors (before the package moved into the monorepo)