auto-generate assists docs and tests

docs/user/assists.md

@@ -0,0 +1,24 @@
+# Assists
+
+## `convert_to_guarded_return`
+
+Replace a large conditional with a guarded return.
+
+```rust
+// BEFORE
+fn main() {
+    <|>if cond {
+        foo();
+        bar();
+    }
+}
+
+// AFTER
+fn main() {
+    if !cond {
+        return;
+    }
+    foo();
+    bar();
+}
+```

docs/user/features.md

@@ -97,11 +97,13 @@ Start `cargo watch` for live error highlighting. Will prompt to install if it's
 
 Stop `cargo watch`
 
-### Code Actions (Assists)
+### Assists (Code Actions)
 
 These are triggered in a particular context via light bulb. We use custom code on
 the VS Code side to be able to position cursor. `<|>` signifies cursor
 
+See [assists.md](./assists.md)
+
 - Add `#[derive]`
 
 ```rust