This change adds a partial that contains a link to the HCL2 issues currently being tracked on GitHub. The partial has been added to the majority of the HCL2 guide documents as a way to help users learn about any open or recently resolved issues pertaining to the HCL2 support in Packer.
* Change generated documentation to indicate what image selection
options are required, and when.
* Refactor the structure of the documentation to highlight required
options for different types of builds