As icon generation turns out to be challenging due to limitations or
native dependencies in node.js libraries for image generation, icon
options are now stubbed out to avoid confusion.
1. Copy help.keyman.com/developer/17.0/* into /developer/docs/help
2. Update references to 18.0 where appropriate
3. Copy all referenced images from /cdn/dev into
/developer/docs/help/images and update links in documentation
Next commit: add deployment to help-keyman-com.sh. Note: simplest way to
test links at this point is to use the help.keyman.com auto deploy and
wait for the PR on help.keyman.com to be validated; we could look at an
internal link validation tool that verifies markdown links?
Relates-to: #12347
