Publish single-HTML versions of developer-guide and user-guide #36
Description
These versions of documents seem to be rendered and cross-referenced with anchors more consistently than chunked-HTML (and single-PDF) docs, as explored in networkupstools/nut#1957 as well as having a single file-name is more future-proof for persistent links. Publishing them on NUT website could facilitate linking from documents, mails, wikis, etc.