[FR] Implement the Help button

[HarikalarKutusu]

This should open a dialog for simple help on:

• About

• Usage (with UI)

• Possible commands in the selected language

• We need a "close help" voice command

Problems:

• We have too much info to show. Paging, tabs etc would make it difficult to navigate, bad UX.
• Also that would add more voice commands
• Content can change rather rapidly with the SW, resulting in multiple tiresome translations.

I think this should be added at a later stage, but an initial version can include possible commands.