Language name support mismatch

[spenserblack]

This command should display each supported ASCII art.

# Runs `onefetch -a Assembly`, `onefetch -a C`, etc.
onefetch -l | while read line; do echo "$line"; onefetch -a $line; done;

Several of these languages will map to unknown, however, causing the default ASCII art to be displayed.
This is because some listed languages have special characters (C++, C#, Objective-C), yet custom ASCII art cannot take special characters.

# doesn't work
onefetch -a C++

# works
onefetch -a cpp

I think it can be a bit confusing if onefetch -l lists the language as "C++", yet that's an invalid input for onefetch -a <ascii_langage>. They should probably match.

It might also help if the help message showed the possible values for -a.