Print the Display Manager

[akshaykhoje]

Feature addition

I wish the program to also show the display manager onto the terminal window in default neofetch execution.

Can also be a flag addition if that's appropriate...

[akshaykhoje]

I wish to work on this feature. Please assign it to me.

[akshaykhoje]

I have made it work, just a little alignment is pending and it'll be good to go. The relevant changes can be seen here @iwamatsu @weslly @vendion @paradigm please have a look... Thank you!