some tps were missing the prune-cell in "nothing to prune"

Author: parmentelat

notebooks/tps/puzzle8/.teacher/README-puzzle8-corrige-nb.md

@@ -25,7 +25,7 @@ Licence CC BY-NC-ND, Thierry Parmentelat
 to tackle this topic, you only need this HTML text, there is no starter code attached
 ````
 
-+++
++++ {"tags": ["prune-cell"]}
 
 ````{admonition} nothing to prune
 :class: warning

notebooks/tps/puzzle8/README-puzzle8-nb.md

@@ -27,14 +27,6 @@ to tackle this topic, you only need this HTML text, there is no starter code att
 
 +++
 
-````{admonition} nothing to prune
-:class: warning
-
-there are no difference - apart from this very cell - between the teacher and the student version, but the notebook is duplicated in .teacher for consistency
-````
-
-+++
-
 ## problem statement
 
 ```{image} media/puzzle8-solving.gif

notebooks/tps/unicode-boxes/.teacher/README-unicode-boxes-corrige-nb.md

@@ -21,7 +21,7 @@ nbhosting:
 
 Licence CC BY-NC-ND, Thierry Parmentelat
 
-+++
++++ {"tags": ["prune-cell"]}
 
 ````{admonition} nothing to prune
 :class: warning

notebooks/tps/unicode-boxes/README-unicode-boxes-nb.md

@@ -23,14 +23,6 @@ Licence CC BY-NC-ND, Thierry Parmentelat
 
 +++
 
-````{admonition} nothing to prune
-:class: warning
-
-there are no difference - apart from this very cell - between the teacher and the student version, but the notebook is duplicated in .teacher for consistency
-````
-
-+++
-
 Unicode comes with a few characters that can be used to draw squares or rectangles on the terminal
 
 See e.g. this page for a list 

notebooks/tps/watson/.teacher/README-watson-corrige-nb.md

@@ -24,7 +24,7 @@ nbhosting:
 
 Licence CC BY-NC-ND, Thierry Parmentelat
 
-+++
++++ {"tags": ["prune-cell"]}
 
 ````{admonition} nothing to prune
 :class: warning

notebooks/tps/watson/README-watson-nb.md

@@ -26,14 +26,6 @@ Licence CC BY-NC-ND, Thierry Parmentelat
 
 +++
 
-````{admonition} nothing to prune
-:class: warning
-
-there are no difference - apart from this very cell - between the teacher and the student version, but the notebook is duplicated in .teacher for consistency
-````
-
-+++
-
 ```{admonition} commencez par télécharger le zip
 {download}`vous aurez besoin du zip qui se trouve ici<./ARTEFACTS-watson.zip>`
 ```