Currently, there is a bunch of SecurePoll documentation all over the place:
https://www.mediawiki.org/wiki/Extension:SecurePoll
https://www.mediawiki.org/wiki/Anti-Harassment_Tools/SecurePoll_Improvements/Understanding_the_STV_result
https://www.mediawiki.org/wiki/Anti-Harassment_Tools/SecurePoll_Improvements
https://wikitech.wikimedia.org/wiki/SecurePoll
We should create a consolidated documentation section on Extension:SecurePoll page and link to all relevant docs from there - outlining what they contain.