docs: update worktree section — auto port detection is now zero-config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ihabadham

docs/building-features/process-managers.md

@@ -334,27 +334,25 @@ wp-server: SERVER_BUNDLE_ONLY=true bin/shakapacker --watch
 
 ## Running Multiple Worktrees Simultaneously
 
-If you use [git worktrees](https://git-scm.com/docs/git-worktree) to work on multiple branches in parallel, each worktree's `bin/dev` will conflict on the default ports (3000 for Rails, 3035 for webpack-dev-server).
+If you use [git worktrees](https://git-scm.com/docs/git-worktree) to work on multiple branches
+in parallel, `bin/dev` automatically detects and avoids port conflicts — no configuration needed.
 
-Create a `.env` file in each worktree (gitignored by default in Rails apps). Both foreman and overmind read `.env` automatically on startup.
+When the default ports (3000 for Rails, 3035 for webpack-dev-server) are occupied, `bin/dev`
+scans for the next free pair and prints:
 
-The generated `Procfile.dev` uses `${PORT:-3000}`, so setting `PORT` is enough for Rails. For the webpack dev server, Shakapacker reads `SHAKAPACKER_DEV_SERVER_PORT` natively on both the Ruby proxy and the webpack-dev-server JS sides — no `shakapacker.yml` changes needed.
-
-**Worktree 1** — use defaults (no `.env` needed), or set explicitly:
-
-```sh
-PORT=3000
-SHAKAPACKER_DEV_SERVER_PORT=3035
+```
+Default ports in use. Using Rails :3001, webpack :3036
 ```
 
-**Worktree 2 `.env`:**
+**To override ports manually**, create a `.env` file in the worktree (gitignored by default).
+A `.env.example` is generated by `rails g react_on_rails:install` as a reference:
 
 ```sh
 PORT=3001
 SHAKAPACKER_DEV_SERVER_PORT=3036
 ```
 
-A `.env.example` is generated by `rails g react_on_rails:install` as a starting point. Copy it to `.env` and adjust ports as needed.
+When `PORT` or `SHAKAPACKER_DEV_SERVER_PORT` are set, auto-detection is skipped entirely.
 
 ## See Also