issue #7701 Appearance of "Set of Faces" in documentation.

Remove gray background and get some indentation
(Note this proposed pull request needs the proposed pull request #7700)

Triangulation/doc/Triangulation/Triangulation.txt

@@ -130,7 +130,7 @@ Two full cells \f$ \sigma\f$ and \f$ \sigma'\f$ sharing a facet are called
 <I>neighbors</I>. A full cell has always exactly \f$ d+1\f$ neighbors.
 
 Possible values of \f$d\f$ (the <I>current dimension</I> of the triangulation) include
-<BLOCKQUOTE>
+\par
 <DL>
 <DT><B>\f$d=-2\f$</B><DD> This corresponds to an empty
 triangulation data structure.
@@ -145,7 +145,6 @@ triangulation of the \f$ 0\f$-sphere.
 <DT><B>\f$ 0< d \le D\f$</B><DD> This corresponds to a triangulation of
 the sphere \f$ \mathbb{S}^d\f$.
 </DL>
-</BLOCKQUOTE>
 
 ## The `Triangulation_data_structure` Class ##