Update preferences.md lines ~300 to 510

- Full stops at the end of sentences
- No full stops at the end of non-sentences
- Capitalization at the beginning of sentences and on proper nouns
- Better wording
- Delete space before commas
- Backtick `key combinations`
- Switch unchecked and checked in the description of one checkbox
- Replace "**Cancel**" by "**Always yes**"

Author: abcbuck