Remove note about using Git for Windows

As discussed in pull request #4013.

pkg/cmd/alias/set/set.go

@@ -52,8 +52,6 @@ func NewCmdSet(f *cmdutil.Factory, runF func(*SetOptions) error) *cobra.Command
 
 			**Platform notes for Windows:**
 
-			- Shell aliases are executed via 'sh' as installed by Git For Windows.
-			  If you have installed git in some other way, shell aliases may not work for you.
 			- If you are using a shell that is *not* Unix-like (e.g. Command Prompt, cmd.exe),
 			  make sure to *double quote* when defining an alias.
 			  For instance, use ` + "`gh alias set pv \"pr view\"`" + ` instead of ` + "`gh alias set pv 'pr view'`.  " +