docs: add svg logos

[adisreyaj]

Adds Horizontal and Vertical NGXS logos in SVG format

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/ngxs/store/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: #1600

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[markwhitfeld]

Awesome work! Nicely done.

[adisreyaj]

Awesome work! Nicely done.

Thanks, @markwhitfeld.
I picked the color from the existing png icon, so it might not be accurate. So If you can provide the brand color code, I can verify and fix it if required.

[markwhitfeld]

You are welcome to add another PR, swapping out the png usages for your svgs 👍

[markwhitfeld]

What you see is what you get regarding colour! Thanks!

[splincode]

[markwhitfeld]

@splincode, do you have any idea why adding an svg file to the assets folder would make the integration test fail its bundle size?