byobu: add page

[sellisd]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
  added in common as it is available for linux and macOS
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known): 6.12

[sebastiaanspeck]

What is the direct relation with tmux and screen?

[sellisd]

byobu can use as a backend either tmux (by default) or screen. They are similar tools but do not serve the exact same purpose. From a user perspective byobu has more features and is more rich than tmux or screen but since it can use them if you know or are familiar with one or the other might be helpful (e.g. you would know the keybindings).