Update README.md

Add id R5401 for sys-exit-used

Author: antonyricard

README.md

@@ -9,6 +9,7 @@ cnes-pylint-extension checks the following rules :
 - R5104 - builtin-name-used
 - R5105 - recursive-call
 - R5106 - use-context-manager
+- R5401 - sys-exit-used
 - R5402 - os-environ-used
 - R5403 - sys-argv-used
 - W9095 - missing-docstring-field