fix xorg low resolution

instructions.md

If cat /var/log/Xorg.0.log | grep -P "Mode is rejected: (Vert|Horiz)", then you probably need to update the monitor section in your xorg.conf.

Example:

Section "Monitor"     
    Identifier     "Dell-P2414Hb"    
    VendorName     "DELL"       
    ModelName      "P2414Hb"             
                                             
    HorizSync      30.0 - 83.0
    VertRefresh    56.0 - 76.0
EndSection

And update the screen section:

Section "Screen"
    # ...
    
    Monitor        "Dell-P2414Hb"
    
    # ...
EndSection

https://forums.geforce.com/default/topic/531709/linux-problem-getting-correct-resolution-on-twinview-using-driver-313-18/