Update readme.md

cheat/readme.md

+## How to install cheat software
 $ sudo pip install cheat
 
-Source: https://github.com/chrisallenlane/cheat
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+## How to use cheat software
+In your terminal, write ```cheat``` followed by a classical command.
+For example, ```cheat tar``` will show:
+```
+# To extract an uncompressed archive:
+tar -xvf /path/to/foo.tar
+
+# To create an uncompressed archive:
+tar -cvf /path/to/foo.tar /path/to/foo/
+
+# To extract a .gz archive:
+tar -xzvf /path/to/foo.tgz
+...
+```
+[Source](https://github.com/chrisallenlane/cheat)
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