slides/sysdev-block-filesystems: use /mnt for mounting

Instead of /tmp, less standard

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>

slides/sysdev-block-filesystems/sysdev-block-filesystems.tex

@@ -360,9 +360,9 @@ \subsection{Using block filesystems}
     modify its contents from the development workstation, using the
     {\bf loop} mechanism:
   \item Example:\\
-    \code{mkdir /tmp/tst}\\
-    \code{mount -t ext4 -o loop rootfs.img /tmp/tst}
-  \item In the \code{/tmp/tst} directory, one can access and modify
+    \code{mkdir /mnt/test}\\
+    \code{mount -t ext4 -o loop rootfs.img /mnt/test}
+  \item In the \code{/mnt/test} directory, one can access and modify
     the contents of the \code{rootfs.img} file.
   \item This is possible thanks to \code{loop}, which is a kernel
     driver that emulates a block device with the contents of a file.