Create a `Learn Log4j in under 2 minutes!` page

[vy]

As agreed in the site structure document, create a "Learn Log4j in under 2 minutes!" page with following goals in mind:

• Outline:
  • pom.xml entries
  • logger.info() (and logger.atInfo(), i.e., the fluent API)
  • Don’t use toString()
  • Don’t printStackTrace() – use last argument
  • Don’t string concatenate – use parameters
  • My first log4j2.xml
  • Provide quick links to manual pages for next steps
• Target 2.x, port to main

[grobmeier]

Added some changes with:
85c61ca
e6ef19f
69169e6
e6ef19f
261b894