git: Tell people about https:// instead of http://

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

slides/kernel-git-content/kernel-git-content.tex

@@ -53,7 +53,7 @@
   \item Cloning Linus Torvalds' Linux kernel repository
     \code{git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git}
   \item \code{git://} is a special Git protocol. Most repositories can
-    also be accessed using \code{http://}, but this is slower.
+    also be accessed using \code{https://}, but this is slower.
   \item After cloning, in \code{linux/}, you have the repository and a
     working copy of the master branch.
   \end{itemize}