* More general descriptions and better title
* Don't use `print` word
* More specific verb in first sample description:
- `display` -> `concatenate`
* Add `-b`/`-r`/`-s` examples
* Duplicate `tac` to `linux/`
* Highlight first option chars
* Add `See also` reference
* Applying the snake_case convention throughout the repo
- Also removing the file extension where not needed
- Adding {{ }} on a few old pages
* Addressing concerns
- Added {{ }} where they were missed out
- Removed spaces inside {{ }}
- Reverting "file" to "filename" to make it clearer
* Fixing the comments on nc page