It's straightforward in the text-based formats used to create man pages (troff) and in subsequent native documentation formats: Texinfo, various Wiki and Markdo

It's straightforward in the text-based formats used to create man pages (troff) and in subsequent native documentation formats: Texinfo, various Wiki and Markdown-inspired syntaxes, etc. It might be that relatively little documentation is created in Word by people who want the process to be as efficient as possible (as opposed to copy-writers who charge by the hour).