Add a Tips a Tricks section for things which are not requirements but useful knowledge to address typical scenarios

[ericzolf]

This issue has been created as a consequence of #67 : it isn't exactly a recommendation, but more a "if you want to support old versions, do this", but we can't recommend supporting old versions, it's a customer/product owner decision resp. requirement unrelated to the actual quality of the code. #35 is another example of such a topic, neither facts nor vars are "better", they just are different in behavior.

[ericzolf]

Agreed to go for a separate section, named "Tips & Tricks".