docs(docs): add iris docs and update shell documentation for iris integration

docs/shell/scripts.mdx

@@ -314,9 +314,9 @@ A task runner that searches every task source in the project and lets you pick o
 
 **Run.** cds into the task's directory and `exec`s the runner. Extra arguments given to `pj` travel to the task through `$PJ_EXTRA` (shell-quoted), with `--` inserted for `npm run`, `mise`, and `devbox`. Tasks named `dev`, `start`, `serve`, `watch`, or namespaced variants like `dev:web` are wrapped in `openlogs` (found on `PATH`, via `mise which`, or in mise's node installs) for a live log tail. Without openlogs they run unwrapped, with a note.
 
-**Env.** `PJ_QUIET=1` suppresses the "no task sources found" error (exit status stays 1). The <kbd>down</kbd> bindings use it. `PJ_STATE=FILE` makes `pj` write `open` to `FILE` before launching the picker, and `pj --run` writes `ran`; the file stays empty when there are no task sources. The key bindings read it to tell no tasks, a cancelled picker, and a task that printed output apart and redraw the prompt to match. `pj` itself does no cursor handling, so typing `pj` behaves like any command.
+**Env.** `PJ_STATE=FILE` makes `pj` write `open` to `FILE` before launching the picker, and `pj --run` writes `ran`; the file stays empty when there are no task sources. The key bindings read it to tell no tasks, a cancelled picker, and a task that printed output apart and redraw the prompt to match. `pj` itself does no cursor handling, so typing `pj` behaves like any command.
 
-**Launched by:** <kbd>ctrl-p</kbd>, and <kbd>down</kbd> on an empty prompt, in fish, zsh, and bash.
+**Launched by:** <kbd>ctrl-p</kbd> in fish, zsh, and bash.
 
 **Needs:** `bash`, `tv`, `mtime-sort`, `jq`, `python3` 3.11+ (for `tomllib`), plus whichever runners the project uses.