Move Stage 5 to the Beginning

[mabolek]

Stage 5 needs to be renamed and moved to the beginning, before Stage 1. Maybe we should call it Stage 0?

We have received feedback indicating that it would be better to have an introduction to TYPO3 as the first step. This step should include the process of learning about TYPO3 and related technologies by seeing it done, rather than through hands-on work. This means it should contain a compressed version of steps 1–4.

• Rename stage
• Rename folder
• Rename anchors
• Check for references to Stage 5 in the introduction texts and rename them