update msys setup readme

tools/MSYS_SETUP.txt

-OpenModelica Included Development Environment-MSYS2+MINGW32/MINGW64
--------------------------------------------------------------------
-Adrian.Pop@liu.se, 2010-10-24, last update: 2017-03-10
--------------------------------------------------------------------
-
-WARNING NOTE:
-- DO NOT DO THIS IF YOU HAVE OMDev installed!
-- this file explains how to setup the msys included in the OpenModelica installation
-
-To check for an updated version of this package go to:
-https://openmodelica.org/svn/OpenModelicaExternal/trunk/tools/windows/OMDev/tools
-
-VERY IMPORTANT INSTALLATION ISSUES!
-***********************************
-
-MSYS setting
-============
-To make things move fast in msys2 one has to generate the group and passwd files on the host.
-Open windows command prompt (cmd) and run %OPENMODELICAHOME%\tools\MSYS_SETUP.bat file.
-
-MINGW32 or MINGW64
-==================
-To build using 32 bit GCC you run:
-%OPENMODELICAHOME%\tools\msys\mingw32_shell.bat
-To build using 64 bit GCC you run:
-%OPENMODELICAHOME%\tools\msys\mingw64_shell.bat
-
-ENVIRONMENT VARIABLE SETTINGS
-=============================
-- note that msys_shell.bat mingw32_shell.bat mingw64_shell.bat
-  + do not use Windows PATH varible. If you want to use the 
-    Windows path variable define an environment varible called
-    MSYS2_PATH_TYPE=inherit
-	or you can call the batch scripts with -use-full-path
-  + do not use Windows TEMP directory but the directory:
-    %OPENMODELICAHOME%\tools\msys\tmp
-	if you want to change this behavior edit:
-	%OPENMODELICAHOME%\tools\msys\etc\profile
-	or define $TEMP and $TMP in the terminal
-- if you want to use the msys shell from Windows command line
-  make sure you set MSYSTEM to one of MSYS, MINGW32, MINGW64
-  if you do:
-  set MSYSTEM=MINGW32 you get the 32 bit GCC (mingw32_shell.bat)
-  set MSYSTEM=MINGW64 you get the 64 bit GCC (mingw64_shell.bat)
-  set MSYSTEM=MSYS use for updating MSYS     (msys2_shell.bat)
-
-Address questions/problems to:
-Adrian Pop,
-Adrian.Pop@liu.se
+OpenModelica Included Development Environment-MSYS2+MINGW32/MINGW64
+-------------------------------------------------------------------
+Adrian.Pop@liu.se, 2010-10-24, last update: 2021-05-16
+-------------------------------------------------------------------
+
+WARNING NOTE:
+- DO NOT DO THIS IF YOU HAVE OMDev installed!
+- this file explains how to setup the msys included in the OpenModelica installation
+
+VERY IMPORTANT INSTALLATION ISSUES!
+***********************************
+
+MSYS setting
+============
+To make things move fast in msys2 one has to generate the group and passwd files on the host.
+Open windows command prompt (cmd) and run %OPENMODELICAHOME%\tools\MSYS_SETUP.bat file.
+
+MINGW32 or MINGW64
+==================
+To build using 32 bit GCC you run:
+%OPENMODELICAHOME%\tools\msys\mingw32.exe
+To build using 64 bit GCC you run:
+%OPENMODELICAHOME%\tools\msys\mingw64.exe
+
+ENVIRONMENT VARIABLE SETTINGS
+=============================
+- note that msys.exe mingw32.exe mingw64.exe
+  + do not use Windows PATH varible. If you want to use the 
+    Windows path variable define an environment varible called
+    MSYS2_PATH_TYPE=inherit
+  + do not use Windows TEMP directory but the directory:
+    %OPENMODELICAHOME%\tools\msys\tmp
+	if you want to change this behavior edit:
+	%OPENMODELICAHOME%\tools\msys\etc\profile
+	or define $TEMP and $TMP in the terminal
+- if you want to use the msys shell from Windows command line
+  make sure you set MSYSTEM to one of MSYS, MINGW32, MINGW64
+  if you do:
+  set MSYSTEM=MINGW32 you get the 32 bit GCC (mingw32.exe)
+  set MSYSTEM=MINGW64 you get the 64 bit GCC (mingw64.exe)
+  set MSYSTEM=MSYS use for updating MSYS     (msys2.exe)
+
+Address questions/problems to:
+Adrian Pop,
+Adrian.Pop@liu.se