Ajout des dates des figures dans les titres

Comme je ne sais pas refaire les figures Indeed, alors autant faire
semblant que ce soit volontaire qu'elles datent un peu.

FormaContinue_MeteoAvril2021/Slides/git.tex

@@ -278,13 +278,13 @@ int main () {
 % plot generated with git
 % https://qa.debian.org/cgi-bin/popcon-png?packages=subversion+cvs+mercurial+rcs+bzr+brz+fossil+darcs+monotone+codeville+tla+git&show_installed=0&show_vote=1&show_old=0&show_recent=0&show_nofiles=0&want_percent=0&want_legend=1&want_ticks=1&from_date=&to_date=&hlght_date=&date_fmt=%25Y-%25m
 
-\begin{frame} \frametitle{Git Adoption (Debian popularity contest)}
+\begin{frame} \frametitle{Git Adoption (Debian popularity contest in 2021)}
   \begin{center}
     \includegraphics[width=.8\textwidth]{fig/popcon-png}
   \end{center}
 \end{frame}
 
-\begin{frame}\frametitle{Git Adoption (Job offers)}
+\begin{frame}\frametitle{Git Adoption (Job offers at the turmoil around 2015)}
   \begin{center}
     \only<1>{\includegraphics[width=.8\textwidth]{fig/jobgraph}}
     \only<2>{\includegraphics[width=.8\textwidth]{fig/jobgraph-proprietary}}