Describe how difftastic works in FAQ

README.md

@@ -132,6 +132,16 @@ $ difft --check-only --exit-code before.js after.js
 This will set the exit code to 0 if there are no syntactic changes, or
 1 if there are changes found.
 
+### How Does It Work?
+
+Difftastic treats structural diffing as a graph problem, and uses
+Dijkstra's algorithm.
+
+My [blog
+post](https://www.wilfred.me.uk/blog/2022/09/06/difftastic-the-fantastic-diff/)
+describes the design, and there is also an [internals section in the
+manual](https://difftastic.wilfred.me.uk/diffing.html).
+
 ## Translation
 
 + [Chinese](./translation/zh-CN/README-zh-CN.md)