Migrate the ImageJ user guide to this website

The [Working with ImageJ](https://imagej.github.io/guide/working-with-imagej) guide page is the result of a partial import of the [ImageJ user guide](https://imagej.nih.gov/ij/docs/guide/user-guide.pdf).

Currently it has a lot of display problems (broken syntax) and missing sections. Possible options:
* Remove the page for now
* Clean up the page

Compare the current Working with ImageJ guide page at imagej.github.io/guide/working-with-imagej with the source ImageJ user guide PDF at imagej.nih.gov/ij/docs/guide/user-guide.pdf. First confirm with maintainers whether the intended outcome is removal or a complete cleanup and migration; done should mean that agreed outcome is completed without the current display problems or missing sections.

Written by the indexing model from the issue text.