Add docs on setting default DeltaE method

docs/color-difference.md

@@ -92,3 +92,19 @@ color1.deltaE(color2, "76");
 color1.deltaE(color2, "CMC");
 color1.deltaE(color2, "2000");
 ```
+
+## Setting the default DeltaE algorithm
+
+Notice that even if you include better DeltaE algorithms such as ΔΕ2000,
+the default DeltaE algorithm used in every function that accepts a deltaE argument (e.g `Color#steps()`) or `color.deltaE()` with no method parameter) will remain DeltaE 1976.
+This is because Color.js doesn't necessarily know which DeltaE method is better for your use case.
+E.g. for high performance code, you may prefer the speed over accuracy tradeoff of DeltaE 1976.
+You can however change this default:
+
+```js
+let color1 = new Color("blue");
+let color2 = new Color("lch", [20, 50, 230]);
+color1.deltaE(color2);
+Color.defaults.deltaE = "2000";
+color1.deltaE(color2);
+```