update readme

Readme.md

+# Instructions
 
-test
+The codes in this package are used to follow the data analysis tutuorials,
+which are prepared for the graduate course of CCNU.
+
+Each sub-directory is corresponding to the .pdf file in twiki. Links for these docments can be found in the twiki, as:
+
+- Shell: [link](https://twiki.cern.ch/twiki/bin/view/Sandbox/CcnuLhcbShell) (03 -- 07)
+- C++: [link](https://twiki.cern.ch/twiki/bin/view/Sandbox/CcnuLhcbCplusplus) (08 -- 12)
+- ROOT: [link](https://twiki.cern.ch/twiki/bin/view/Sandbox/CcnuLhcbRoot) (13 -- 16)
+- Advanced ROOT: [link](https://twiki.cern.ch/twiki/bin/view/Sandbox/CcnuLhcbAdvanceRoot) (17 -- 21)
+
+If you have any suggestions regarding to any of docments, please contact me, via [hyin AT cern.ch].
+
+The first version was upolad to this package at Jan. 15th, 2023.
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