Fix and extend color documentation

[Kissaki]

• Drop ambiguous hash label - works just fine with only the symbol #
• Clarify when it is commented out vs may be (hex) value
• Drop text table of contents; the website has it's own sidebar table of contents / headline jump list
• Fix headline levels - the general color declaration docs were under Table Borders, and hex and full hex were not on the same level, and primitives had a sub-headline one level too deep
• Introduce/Rename main section 'Color Configuration'
• Show command to print the current configuration
• Add closure declaration format documentation
• Drop separators following headlines; other headlines do not have this, they make no logical sense, and they lead to double-separator-lines being rendered on the website

Resolves #1503

[fdncred]

I made a couple comments above.

I'm not sure the documentation covers it well but there's a nuance to coloring and theming and that is, coloring can also be controled by your terminal theme. For named colors like green, there are ansi escape codes that are emitted. So, green is "\e[32m". Your terminal can define 32m as a completely different color. The only real way to get "green" would be to use a terminal that supports 24-bit colors and to specify it as #00ff00`. These hex colors don't use the escape codes like 32m.

I'm not saying you need to put this in this PR, and I definitely didn't explain it very well, but coloring is kind of weird.

[Kissaki]

I think I get what you mean. I'll not cover that in this PR though, it already has multiple concerns, and it's not part of the docs before either.

[fdncred]

Thanks for the updates. I found a couple more things that are incomplete.

[fdncred]

Thanks