📝 Fix broken Velleman K8400 links (#1046)

config/examples/Velleman/K8400/README.md

@@ -0,0 +1,22 @@
+# Velleman K8400 Vertex Configuration
+
+Source: [velleman.eu](https://www.velleman.eu/products/view/?id=417866)
+
+Configuration files for the K8400, ported upstream from the official Velleman firmware.
+Like its predecessor, (K8200), the K8400 is a 3Drag clone. There are some minor differences, documented in `pins_K8400.h`.
+
+Single- and dual-head configurations provided. Copy the correct `Configuration.h` and `Configuration_adv.h` to the `/src/config` directory.
+
+> [!NOTE]
+> This configuration includes the community sourced feed rate fix. Use 100% feed rate in Repetier!
+
+### Original Sources
+
+Upstreamed from:
+
+[birkett/Vertex-K8400-Firmware on GitHub](https://github.com/birkett/Vertex-K8400-Firmware)
+
+Credit to Velleman for the original Marlin 1.0.x based code:
+
+- [Download Vertex M1 1.4-H1](https://cdn.velleman.eu/downloads/files/vertex/firmware/vertex-m1-v1.4-h1.zip)
+- [Download Vertex M1 1.4-H2](https://cdn.velleman.eu/downloads/files/vertex/firmware/vertex-m1-v1.4-h2.zip)