feat: add highlight for nvim-treesitter-context

[smjonas]

Before:

After:

I simply used the same highlights as SignColumn.

[smjonas]

Maybe we should choose a lighter highlight color instead so it does not fade into the background as much?

[smjonas]

I kind of like colors.selection:

[rmehri01]

Hey again, thanks for the PR!

I personally prefer the more subtle active background and I think this should be the default since the plugin seems to take from NormalFloat but you can always override this in your own config if you want.

Also do you mind adding this plugin to the list of supported ones for documentation?

[smjonas]

Hey, ok then let's leave it set to active. I added the plugin to the list of supported plugins in the readme.

[rmehri01]

Sounds good! And also, sorry I should have specified but there's both the readme and the vim help docs: https://github.com/rmehri01/onenord.nvim/blob/main/doc/onenord.nvim.txt.

[smjonas]

No worries, thanks for reminding me :)

[rmehri01]

Looks great, thanks again!

[smjonas]

Thanks for your work on this great color scheme! :D