ScaleManager documentation updates

- Clarified proper usage of `pageAlignVertically` and add note about 2.2
  change and how to obtain 2.1 behavior.

- Removed the `@readonly` status of the `parentIsWindow` and `parentNode`;
  these can be updated in a controlled manner.

- Added intra-hyperlinks

- Updated some ancillary documentation
Merge pull request #1428 from pnstickne/wip-1422-vertical-align

ScaleManager documentation updates