Yes, that appears to be the case. (Which in itself is a bit suspicious. Why would they remove it if they thought they had nothing to hide?)

Anyway, it was archived:

https://web.archive.org/web/20190416030526/https://docs.oton...

https://archive.fo/QiMY9

The full list of archived otonomo doc pages:

https://web.archive.org/web/*/https://docs.otonomo.io/docs/*

https://archive.fo/docs.otonomo.io

It is still here: http://otonomo-docs.readme.io/docs

(found on another internal forums/board) Save a copy maybe?