add syntax highlight

Debian-Upgrade.md

@@ -6,7 +6,7 @@
 
 Before upgrading, upgrade and repair existing problems:
 
-```bash
+```console
 apt-get update
 apt-get upgrade
 apt-get full-upgrade
@@ -41,7 +41,7 @@ Notes:
  - keep existing configs as desired
  - let GRUB re-install to the boot disk
 
-```bash
+```console
 apt-get update
 apt-get upgrade --without-new-pkgs
 apt-get full-upgrade
@@ -51,7 +51,7 @@ apt-get full-upgrade
 
 Some upgrades change behaviour and need to be reverted prior to a reboot, such as this bugfix in the D11 kernel which is incompatible with the D12 kernel:
 
-```bash
+```console
 $ cat /etc/modprobe.d/iwlwifi.conf
 # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=969264
 #options iwlwifi enable_ini=N
@@ -61,7 +61,7 @@ This setting must be disabled prior to reboot or the `iwlwifi` module will fail
 
 ## Reboot
 
-```bash
+```console
 reboot
 ```
 
@@ -69,7 +69,7 @@ reboot
 
 Look for strays, "rc" tends to mean it can be purged (was to be removed, failed):
 
-```bash
+```console
 apt-get autoremove --purge
 dpkg -l | grep -v ^ii
  ...
@@ -80,7 +80,7 @@ apt-get purge python
 
 Look for installed packages not in the repo anymore:
 
-```bash
+```console
 aptitude search "?installed?not(?narrow(?installed,?origin(^Debian$)?archive(^stable)))"
 
 i A cpp-10                          - GNU C preprocessor
@@ -101,7 +101,7 @@ i A linux-image-5.10.0-26-amd64     - Linux 5.10 for 64-bit PCs (signed)
 
 Remove the packages which are safe and their unnecessary dependencies:
 
-```bash
+```console
 apt-get remove --autoremove --purge cpp-10 gcc-10 gcc-10-base \
   gcc-9-base libbpf0 libdns-export1110 libffi7 libgcc-10-dev \
   libisc-export1105 libprocps8 libruby2.7 libsepol1 libssl1.1 \
@@ -110,7 +110,7 @@ apt-get remove --autoremove --purge cpp-10 gcc-10 gcc-10-base \
 
 Run a quick metadata clean on apt, it should show messages about deleting old index data, packages or other legacy data.
 
-```bash
+```console
 apt-get autoclean
 ```