Events: Add social media share image & description.

[StevenDufresne]

We need to add social media share tags.

We can use the showcase code as inspiration.

@WordPress/meta-design Can we get an image? Here's showcase's image for sizing.

[jasmussen]

This is a first draft just to have something ready.

If @fcoveram gets a chance to refine this, I would defer to any design he makes as superior. Here's the Figma.

[fcoveram]

I don't think the W symbol is necessary. I reused the style of Showcase with a white and blueberry mix.

[thetinyl]

@StevenDufresne Suggesting the following for the description:

Find upcoming WordPress events near you and around the world. Join your local WordPress community at a meetup or WordCamp, or learn how to organize an event for your city.