Make boot-deploy config be vendor customization, relocate to /usr/share
The configuration from boot-deploy comes from the deviceinfo package. Adding another file where any kind of configuration can be added increases the risks of making mistakes and start pushing any kind of configuration to it. Since the file was born for other distros to be able to configure boot-deploy[1][2], let's reflect that in the file name. In the process, move the file to /usr/share from /etc, since it is not a user-owned (host- specific) but a distro-owned (should not be modified) file.
Also, update the documentation corresponding to the file, since both the file and all its variables are boot-deploy requirements.
[1] !18 (comment 1177011687) [2] !18 (comment 1177011689)
@jenneron @InsanePrawn, I did this after discussing with craftyguy on reducing the places were we place configuration, related to https://gitlab.com/postmarketOS/pmaports/-/issues/1836#note_1267128361. Since we do not want the mistake again, I moved the file to /usr/share and clarified that it is only expected to contain vendor customization. Is there anything against this?