Merge 'Documentation guidelines' and 'Documentation style guide'
I'm wondering why we have two different pages for that... and merging them would put everything in a single place.
If at some point if become too much for a single page we could try having a more elaborate navigation. Like on https://developers.google.com/style/.
I also think we should structure the different entries better, maybe having different sections for:
- General style: punctuation, capitalization, etc.
- Formatting: CSS, screenshots, etc.
- Usage dictionnary: Tails terms and other technical terms.