Banner Updates for Forum 2.0

This issue is to make the following changes to the Forum banner following the Example image below:

- Change the banner's font to [Proto Mono.zip](https://github.com/iotexproject/forum-plugin/files/9201168/Proto.Mono.zip).
- Change the background image to the one included below:

- Change the forum logo to the one included below (and maintain the link to [iotex.io](https://iotex.io/) if possible):

- Change the call-to-action of the green button's text to "GET STARTED WITH THE FORUM" and delete the current link. The new link is: https://iotex.io/blog/welcome-iotex-forum/

- Change the icons under "Follow Us" to [green icons.zip](https://github.com/iotexproject/forum-plugin/files/9201399/green.icons.zip). Links are: [Twitter](https://twitter.com/iotex_io), [Discord](https://iotex.io/devdiscord), [YouTube](https://www.youtube.com/channel/UCdj3xY3LCktuamvuFusWOZw), [Reddit](https://www.reddit.com/r/IoTeX/), [Telegram](https://t.me/IoTeXGroup), [GitHub](https://github.com/iotexproject).

- After updating the icons, delete "→ Github" from under "Learn More".