Improve docs for scribble_glyph_set()

[JustAGuyAFAIK]

Hello! I would like to request a small change to the Scribble docs, specifically with scribble_glyph_set. I initially made the assumption that, if I wanted to change kerning for all characters in a font, I would need to set them all individually, but it was only until I looked into the script itself and realized I could have just used the all keyword. But before I even realized that, I had initially used scribble_font_bake_outline_and_shadow and set the outline mode to none, then set the separation argument to whatever I'd like and that worked too.

To prevent other people from struggling like this, I think it'd be great if Target character, as a string was changed to Target character, as a string (or put "all" if you would like all characters to be targeted). It would also be great if "all" was just the default argument if the user didn't set the argument themselves.

[JujuAdams]

Changing default behaviour of a function would be a breaking change and therefore not possible until the next major version update (version 10).

Please make a minimal PR for the suggested change and I will take a look.

[JustAGuyAFAIK]

I would, but I don't exactly know how to do that. (still new to the site)
but the proposed changes would look like this: