Adjust styling spec to specify "bright" ansi names and format document

[JamyGolden]

• Add "Gray" and "Light Gray" to Terminal column for base03 and base04
• Mention bright variants in Terminal column and specify bright variants first since we consider these colors bright
• Remove ANSI colour 3 from base09 since this is specified to be orange, not yellow or bright yellow.
• Put Terminal column colors in brackets if they colour name is not referring to an ANSI color name
• Format table to make it easier to read in markdown
• Add backticks to references to base0x properties
• Bump styling spec version to 0.4.1

[JamyGolden]

I've just pushed a change to assume the non-bright variants are "default" or first-class by mentioning them first. Either way it doesn't really play a big role in this spec, but it has an affect on scheme-systems that are a superset of base16, such as base24. Base24 assumes 08-0E are less-saturated/non-bright so I feel like this change is a good addition without breaking superset scheme-systems (not that we can't break them in future, just there isn't a strong enough reason to break them now).

[FredHappyface]

Yeah absolutely happy with this :)