Update src/debug/tester/readme.md

The instructions reference tester.c:tester_set_params, but that function doesn’t exist in src/debug/tester/tester.c (test selection happens in tester_init(), and runtime configuration is handled by tester_set_configuration()).

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Liam Girdwood <lgirdwood@gmail.com>

Author: lgirdwood

src/debug/tester/readme.md

@@ -49,6 +49,6 @@ It strictly `depends on IPC_MAJOR_4`. You cannot instantiate this tester under t
 
 Developers diagnosing tricky hardware bugs can extend the tester by:
 
-1. Adding a new case switch in `tester.c:tester_set_params`.
+1. Adding a new case to the test selection switch in `tester.c:tester_init()` (and, if needed, extending runtime handling in `tester_set_configuration()`).
 2. Defining a new `test_runner()` C file implementing their data patterns.
 3. Adding the target configurations in `tester.toml` to automatically sync with the module offset calculators (`llext_offset_calc`).