Feature/New Meetups page

[DawidRyczko]

What is PR about?

Added a new section "Meetups" with the archive of all meetup events.
Added a new scaffold script to generate new meetups.
Updated README with instructions on how to create a new meetup

Checklist:

• [ x] I am added to the list of authors correctly.
• [ x] All images used in the post is in the correct folder (assets/images/post/).
• [ x] My article has been reviewed internally before opening this Pull Request.
• [ x] I have not modified someone else's previously published articles.
• I double checked my changes locally at http://127.0.0.1:4000/ after running bundle install && bundle exec jekyll serve.
• [ x] My changes generate no new errors