[openstreetmap/openstreetmap-website] SotM Africa 2025 Conference Banner (PR #6473)

[Emmanuel Jolaiya]

### Description

This PR adds the banner configuration for SotM Africa 2025 in the`config/banners.yml` as recommended in the [guideline](https://github.com/openstreetmap/openstreetmap-website/blob/master/FAQ.md#how-do-i-create-a-banner-to-promote-my-openstreetmap-event).

I also cleaned up the past State of the Map (SotM) 2025 Global conference.

Closes #6472.

### Todo

- [ ] Fix the banner constrast and publish the PR.
You can view, comment on, or merge this pull request online at:

  https://github.com/openstreetmap/openstreetmap-website/pull/6473

-- Commit Summary --

  * chore: cleaned up past conference
  * feat: added sotm africa details in banners config

-- File Changes --

    M config/banners.yml (17)

-- Patch Links --

https://github.com/openstreetmap/openstreetmap-website/pull/6473.patch
https://github.com/openstreetmap/openstreetmap-website/pull/6473.diff

-- 
Reply to this email directly or view it on GitHub:
https://github.com/openstreetmap/openstreetmap-website/pull/6473
You are receiving this because you are subscribed to this thread.

Message ID: <openstreetmap/openstreetmap-website/pull/6473 at github.com>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/rails-dev/attachments/20251023/e2038ca4/attachment.htm>