sched_ext: Documentation: Update instructions for running example schedulers

Since the artifact paths for tools changed, we need to update the documentation to reflect that path.
Signed-off-by: Devaansh-Kumar <devaanshk840@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Documentation/scheduler/sched-ext.rst

@@ -66,7 +66,7 @@ BPF scheduler and reverts all tasks back to CFS.
 .. code-block:: none
 
     # make -j16 -C tools/sched_ext
-    # tools/sched_ext/scx_simple
+    # tools/sched_ext/build/bin/scx_simple
     local=0 global=3
     local=5 global=24
     local=9 global=44