yocto: slides: remove "Exclusion" slide

This is not considered very useful. Additionally, the last bullet is not
true anymore as of Kirkstone: PACKAGE_EXCLUDE works with DEB as well.

Since the section is now left with one slide only, also reword section and
slide titles.

Suggested-by: Alexandre Belloni <[email protected]>
Signed-off-by: Luca Ceresoli <[email protected]>

slides/yocto-advanced/yocto-advanced.tex

@@ -285,10 +285,10 @@ \subsection{Package variants}
   \end{itemize}
 \end{frame}
 
-\subsection{Packages}
+\subsection{Selection of packages to install}
 
 \begin{frame}
-  \frametitle{Selection}
+  \frametitle{Selection of packages to install}
   \begin{itemize}
     \item The set of packages installed into the image is defined by
       the target you choose (e.g. \code{core-image-minimal}).
@@ -301,19 +301,6 @@ \subsection{Packages}
   \end{itemize}
 \end{frame}
 
-\begin{frame}
-  \frametitle{Exclusion}
-  \begin{itemize}
-    \item The list of packages to install is also filtered using the
-      \code{PACKAGE_EXCLUDE} variable.
-    \item If you choose to not install a package using this variable
-      and some other package is dependent on it (i.e. listed in a
-      recipe's \code{RDEPENDS} variable), the OpenEmbedded build system
-      generates a fatal installation error.
-    \item This only works with RPM and IPK packages.
-  \end{itemize}
-\end{frame}
-
 \subsection{The power of BitBake}
 
 \begin{frame}