Implement 'Organizing an Ethereum event' banner on /community/events

[isabelladebrito]

Description

Add a banner on ethereum.org/community/events to share the "Organizing an Ethereum event" new page (see #15287)

Where to place the banner

On ethereum.org/community/events, between the "Upcoming events" and "Ethereum meetups" sections

Banner design and copy

1. Use the same banner design from the 'contributor quiz', available at /contributing (see image below)

Copy:

Planning an Ethereum event?
Check out the Ethereum event guide built by the community, for the community.

[button] Read the guide
[link] https://ethereum.org/community/events/organizing (page to be created - see #15287)