Use official Kotlin logo

[Saecki]

The kotlin logo in this repository is one I've never seen before. I think most users are more familiar with the one available here, which is also on their official website.

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	 viewBox="0 0 500 500" style="enable-background:new 0 0 500 500;" xml:space="preserve">
<g id="Logotypes">
	<polygon points="500,500 0,500 0,0 500,0 250,250 	"/>
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</svg>

[goyalyashpal]

i have seen this one too somewhere - it was used in old versions iirc - and frankly "official icons" are not a target for custom icon themes anyway.
for example i saw 4 different icons used for perl language in 4 different themes.

so, the current one seems to befitting the theme, and i would vote against changing it just to match the official one.

[Saecki]

I mean most logos look pretty similar to their official counterparts. The logo here was replaced no later than 2016 by the orange blue one that is shaped the same as the current one. I didn't even recognize this as the kotlin logo.