lightdm: workaround for troubleshooting added

wiki/linux/lightdm.md

@@ -172,3 +172,8 @@ password-border-width = 2px
 # The border radius of the password input.
 password-border-radius = 0.341125em
 ```
+
+## Troubleshooting
+
+If it comes to problems that deny the login it can be useful to switch to another tty.
+This can be done by hitting the key combination `CTRL+ALT+F2`.

wiki/linux/v4l2.md

@@ -20,11 +20,7 @@ To use v4l2loopback an according
 package needs to be installed.
 Some distributions have a package named `v4l2loopback-dkms` in the package
 manager, making the manual installation process unnecessary.
-
-Make sure to
-[start the service](/wiki/linux/systemd.md#startstopenabledisable-a-service) by
-running `systemctl start v4l2loopback.service` and/or enable it to start after each
-boot with `systemctl enable v4l2loopback.service`.
+Make sure that both `dkms` and `linux-headers` packages are installed aswell.
 
 ### Usage
 
@@ -75,10 +71,12 @@ Note the line starting with `ExecStart=/bin/` is the same line described in the
 [above section](#create-temporary-v4l2-devices).
 Make sure to change it if needed.
 
-Afterwards enable the service to start at every boot process by running:
+Afterwards enable the service to start at every boot process aswell as running it by using the
+following command:
 
 ```sh
 sudo systemctl enable v4l2loopback
+sudo systemctl start v4l2loopback
 ```
 
 ## Troubleshooting