added the different block types (alert, example)

demo.tex

@@ -134,12 +134,25 @@ or show \textbf{bold} results.\end{verbatim}
   \end{table}
 \end{frame}
 \begin{frame}{Blocks}
-
+  There are 3 different block enivironmnents already defined. The normal block uses the normal color, ...
   \begin{block}{This is a block title}
     This is soothing.
   \end{block}
-
 \end{frame}
+\begin{frame}{Blocks}
+  ... the alert block the alert color ....
+  \begin{alertblock}{This is an alert block title}
+    This is soothing.
+  \end{alertblock}
+\end{frame}
+\begin{frame}{Blocks}
+  ... and the example block the example color.
+  \begin{exampleblock}{This is an example block title}
+    This is soothing.
+  \end{exampleblock}
+  The blocks can have a background (option \texttt{blockbg}) or not.
+\end{frame}
+
 \begin{frame}{Math}
   \begin{equation*}
     e = \lim_{n\to \infty} \left(1 + \frac{1}{n}\right)^n