provide script to refresh shortcut icon after renaming installation dir (#359)

README.md

@@ -57,6 +57,13 @@ Portable installation does not install any start menu or desktop shortcuts
 and no context menu entries. It creates a shortcut in the selected 
 portable installation folder to start the default WSL distribution.
 
+Note: For an update installation, either the parent directory or the target 
+directory itself can be selected.
+
+Note: If you rename or move the installation directory, the icon of the 
+“WSL Terminal Portable” shortcut will not work anymore; re-run the 
+install-portable.bat script in the installation folder to refresh it.
+
 #### Installation from archive ####
 
 In case a local anti-virus guard barfs about the wsltty installer, the 

install-portable.bat

@@ -2,6 +2,13 @@
 
 chcp 65001 > nul
 
+if not exist "WSL Terminal Portable.lnk" goto install
+echo Rebuilding WSL Terminal Portable shortcut
+set instdir=%~dp0
+goto shortcut
+
+:install
+
 echo Installing WSL Terminal Portable
 echo Select target folder in popup dialog ...
 
@@ -25,6 +32,13 @@ rem call main installation
 call install "%instdir%" "%instdir%" /P
 rem this already changes into "%instdir%"
 
+rem copy additional portable installation files
+rem do this after call install as that deletes previous .bat files
+copy "%~dp0\install-portable.bat" .
+dir "%instdir%"\install-portable.bat
+
+:shortcut
+
 rem create shortcut
 cd /D "%instdir%"
 rem set drive-relative path for shortcut working directory and icon