* Add sections
* `COUNTS WITH MOTIONS`
* `SELECTING LINES`
* `UNDOING`
* Adjust lesson spacing to conform to page-wise scrolling
Vertical length of lessons reduced by 1 line so that page-up and
page-down move cleanly between lessons.
* Add sections
* `THE CHANGE COMMAND`
* `RECAP`
* `MULTIPLE CURSORS`
* Fix height of `RECAP` section
* Fix typo in `MULTIPLE CURSORS`
* Add additional information about space mode to `MULTIPLE CURSORS`
* Change `<SPACE><SPACE>` to `,`
* Add sections
* `THE SELECT COMMAND`
* `SELECTING VIA REGEX`
* `COLLAPSING SELECTIONS`
* Fix quote inconsistency
* Create `docs/tutor.txt`
* Create `EXITING HELIX` and `DELETION` sections
* Create Insert mode, saving, and recap sections
* Create `MOTIONS AND SELECTIONS` section
* Add additional notes to `SAVING A FILE` section
* Remove extra blank lines in `SAVING A FILE` section
* Move `tutor.txt` to `runtime/`
* Add WIP message to end of tutorial
