add explaination on some question.

Author: Readon

README.md

@@ -1,8 +1,7 @@
 # MSYS2 Installer
 
-## Nightly build
-
-https://github.com/msys2/msys2-installer/releases/tag/nightly-x86_64
+This project is to make a installer to helping on setup a working msys2 environment for developping SpinalHDL design, in one step, offline.
+The installer in the (release)[https://github.com/Readon/msys2-installer/releases] directory of this repos contains separate versions of the SpinalHDL jar file, released with the same version number as the version of the SpinalHDL libraries contained therein.
 
 ![screenshot](screenshot.png)
 
@@ -28,6 +27,11 @@ Installing the self extracting archive to `C:\msys64`:
 
 ## FAQ
 
+### How can I seperate the msys2 environment from Windows?
+
+The interference could lead a mess up environment variable management. 
+Start a console from any of your favourite terminal by `msys2_shell.cmd -defterm -no-start -mingw64` can start a standalone environment.
+
 ### What's the difference between the installer and the archives?
 
 The installer provides some additional features such as installing shortcuts, registering an uninstaller, a GUI for selecting the installation path and automatically running a login shell at the end to initialize the MSYS2 environment.
@@ -36,4 +40,12 @@ If you unpack the archives and run a login shell once, you will get a functional
 
 ### What is contained in the installer/archives?
 
-It contains the [base](https://packages.msys2.org/package/base) package and all its dependencies. You can list the contained packages using: `pactree base -lu | sort`
+It contains the [base](https://packages.msys2.org/package/base) package with others required packages by SpinalHDL runing and debugging, and all their dependencies. You can list the contained packages using: `pactree base -lu | sort`
+
+### Why install jdk through sdkman?
+
+The java environment is install through [sdkman](https://sdkman.io/) which helps to provide a standalone environment seperate from host Windows. So that portable using is possible. Java and sbt are all managed by sdkman in it's own directory `/sdkman`. On other way, jar cache file is installed in `/cache` so that we can use the installer offline.
+
+### What if I want to use an old version SpinalHDL?
+
+create issue, or clone this repos and modify yourself.