Update powershell.asc

Fix typing error actually it is "AllUsers" and not "LocalMachine for "Install-Module". Sorry for that mistake, I've mixed that up in my last commit.

Author: Klaus Frank

book/A-git-in-other-environments/sections/powershell.asc

@@ -3,7 +3,7 @@
 
 (((powershell)))(((tab completion, powershell)))(((shell prompts, powershell)))
 (((posh-git)))
-The standard command-line terminal on Windows (`cmd.exe`) isn't really capable of a customized Git experience, but if you're using Powershell, you're in luck.
+The legacy command-line terminal on Windows (`cmd.exe`) isn't really capable of a customized Git experience, but if you're using Powershell, you're in luck.
 A package called Posh-Git (https://github.com/dahlbyk/posh-git[]) provides powerful tab-completion facilities, as well as an enhanced prompt to help you stay on top of your repository status.
 It looks like this:
 
@@ -29,7 +29,7 @@ More information about the requirements: (https://docs.microsoft.com/en-us/power
 [source,powershell]
 -----
 > Update-Module PowerShellGet -Force
-> Install-Module Posh-Git -Scope LocalMachine
+> Install-Module Posh-Git -Scope AllUsers
 -----
 If you want to install Posh-Git only for the currnet user and not globaly, use "-Scope CurrentUser" instead.