Create README_PL.md

Origin questions translated do Polish version
initial translations
translate intro
translate general section
Update Russian/README_RU.md
Merge pull request #36 from lukasz-jakub-adamczuk/patch-1

Create README_PL.md
Merge pull request #37 from draev/patch-1

Update Russian/README_RU.md
Movied polish version to its own folder
Removed polish version from root
translate HTML section
Update Polish/README_PL.md
Merge pull request #38 from pulkowski/patch-1

Update Polish/README_PL.md
translate 'fun' section
translate jQuery section
translate JS code section
translate CSS section
translate JS section
finishing touches
Danish translation
line break removed