runtime/colors/README.txt may contain outdated information

[romainl]

For example, this line is not needed anymore and I'm not sure it ever was.

The suggested boilerplate should match the content of the colorschemes distributed with Vim.

[chrisbra]

It is still used by default.vim. I think this warrants the line to be still there.

[romainl]

That file contains instructions for how to write new colorschemes. How default is written is irrelevant.

[habamax]

I think these 2 lines are redundant:

	highlight clear Normal
	set background&

for dual-background colorschemes in general. I am not talking about background autodetection being mostly wrong, but for the usual flow: user sets background to 'dark' or 'light' and expects colorscheme that supports it to act accordingly.

Here colorscheme is resetting background and will always use "detected" one, no matter what user wanted.