Update cheatsheet.en.md

12.temporary_ins/08.conservative-vector-fields/20.conservative-vector-fields-properties/20.overview/cheatsheet.en.md

@@ -8,6 +8,12 @@ lessons:
       order: 1
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-#### The conservative force fields and their properties
+!!!! *LESSON  UNDER  CONSTRUCTION :* <br>
+!!!! Published but invisible: does not appear in the tree structure of the m3p2.com site. This course is *under construction*, it is *not approved by the pedagogical team* at this stage. <br>
+!!!! Working document intended only for the pedagogical team.
+
+<!--MetaData : ... -->
+
+##### The conservative force fields and their properties
 
 to build
\ No newline at end of file