docs: simplify branch comparison example

README.md

@@ -95,14 +95,9 @@ the measured command:
 hyperfine \
     --parameter-list branch main,performance-improvements \
     --setup 'git switch {branch}' \
-    'rails runner true'
+    'python main.py'
 ```
 
-Make sure your working tree is clean before switching branches. Because this `--setup` command
-changes the checkout, the repository will remain on the last branch from `--parameter-list`
-after the benchmark finishes. If you want to benchmark uncommitted changes, consider using
-`git worktree` and benchmarking the same command in each worktree instead.
-
 ### Intermediate shell
 
 By default, commands are executed using `sh` on Unix (resolved through `PATH`) or `cmd.exe` on Windows.