Use a single note in the debugger documentation

Better wording of the note, move the limitation to the main text. Also switch
to "attention".

See #633.

docs/Modding/Tilesets/debugger.rst

@@ -8,10 +8,10 @@ inspect how the map is drawn. This is very helpful when developing a tileset, to
 understand why something is rendering incorrectly or to understand how other
 tilesets work.
 
-.. note::
-  If you have suggestions regarding the contents and functionality of the
-  debugger, you're very welcome to let us know on `Github`_ --- you'll get a
-  chance to shape it to your needs.
+.. attention::
+  The Tileset Debugger is still a work in progress. If you have suggestions
+  regarding its contents and functionality, you're very welcome to let us know
+  on `Github`_ --- you'll get a chance to shape it to your needs.
 
 To start using the debugger, click on the :guilabel:`Pick tile` button and then
 somewhere on the map. The window will be updated with the list of sprites used
@@ -25,7 +25,8 @@ to draw the selected tile:
 The list has two levels. Each top level item corresponds to one layer used to
 draw the map. When something is drawn for a layer, its image is added next to
 its name and the individual sprites are added in the second level. The sprites
-at the top of the list are drawn first and are hidden by the ones below.
+at the top of the list are drawn first and are hidden by the ones below. Note
+that at the moment, only sprites that correspond to the tile (as opposed to its corners and edges) are visible.
 
 In the picture above, which uses the `amplio2` tileset, the four layers of a
 forest tile are shown, two of which have sprites: ``Background``. a terrain
@@ -40,9 +41,4 @@ the vertical axis that runs from top to bottom. Depending on the type of layer,
 these values may be computed automatically, so they do not necessarily
 correspond to a parameters in the ``tilespec`` file.
 
-.. note::
-  The Tileset Debugger is still an experimental feature with important
-  limitations. In particular, it only shows sprites that correspond to the
-  tile as opposed to its corners and edges.
-
 .. _Github: https://github.com/longturn/freeciv21/issues/new?assignees=&labels=Untriaged%2C+enhancement&template=feature_request.md&title=