ENCODERS.md: minor fixes.

encoders/ENCODERS.md

@@ -304,6 +304,8 @@ alternative is to use two d-type flip-flops on each channel, clocked using a
 signal from the host. Typically this might be produced by a PWM channel running
 continuously. Clock rate depends on the expected worst-case interrupt latency.
 
-This [Wikipedia image](https://en.wikipedia.org/wiki/Incremental_encoder#/media/File:2FF_synchronizer.gif)
-illustrates the idea, along with the metastability problem.
+This Wikipedia image illustrates the idea, along with the metastability problem
+discussed in [the article](https://en.wikipedia.org/wiki/Incremental_encoder).
 
+![Image](./synchroniser.png)  
+By Lambtron - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=86059204