Add CentOS icon

[foo-dogsquared]

Issue: #1160

Checklist

• I updated the JSON data in _data/simple-icons.json
• I optimized the icon with SVGO or SVGOMG
• The SVG viewbox is 0 0 24 24

Description

The brand color is chosen based from the official website.
Although there is the official palette for the logo, it seems there's no mention of the color for the branding.

[birjj]

Can you please elaborate a bit more on how you got the color from the website? I can't seem to find a match.

I think I would personally prefer using one of the defined colors for the logo. I don't think any one color on their website is dominant enough to be considered the brand color, although given that the website is dark blue we might want to pick the dark blue logo color (otherwise the choice between the three logo colors is pretty arbitrary). Thoughts @ericcornelissen @foo-dogsquared?

[foo-dogsquared]

I got the color from this particular CSS rule:

#wrap {
	background-image: radial-gradient(ellipse at center top, rgba(32,74,135,0.8) 20%, rgba(0,0,0,0) 100%);
	background: -webkit-radial-gradient(center top, ellipse cover, rgba(32,74,135,0.8) 20%,rgba(0,0,0,0) 100%);
}

I agree with the chosen color, @birjolaxew .
From the website, wiki, and motfis, the dominant color is blue so it is logical to choose the dark blue color (#262577) from the palette.