remove the nushell chapter from install doc: it doesn't work anymore

Related: Canop#375

CHANGELOG.md

@@ -2,6 +2,7 @@
 #### Minor changes:
 - modal mode: revert to command mode on command execution - Fix #372
 - modal mode: when in command mode, '/' only enters input mode and is never appended to the input
+- better handle failing external programs when not leaving broot
 #### Major feature: staging area
 Yoy may add files to the staging area then apply a command on all of them. This new feature is described [here](https://dystroy.org/broot/staging-area).
 Several verbs have been added. Type "stag" in help to see them all.

website/docs/install-br.md

@@ -29,12 +29,6 @@ If you prefer to manage the function sourcing yourself, or to automate the insta
 
 `broot --set-install-state installed` tells broot the `br` function is installed (other possible values are `undefined` and `refused`).
 
-# `br` alias for Nushell
-
-As a shortcut for [Nushell](https://www.nushell.sh/), define the following alias:
-
-    def br [] { broot | trim | cd $it }
-
 # `br` alias for Xonsh shell
 
 The shortcut for [xonsh](https://xon.sh/) shell can be installed with using [xontrib-broot](https://github.com/jnoortheen/xontrib-broot)