Verify all texts grammatically and stylistically

[darowsluk]

As a user I want to read clear texts with good style and without grammatical errors.

Testing for:

• [x] 1. Grammatical errors (spelling, etc.)
• [x] 2. Consequent style (person and number)
• [x] 3. Logic
• [x] 4. Open and concise style
• [x] 5. Short paragraphs