Not currently, sorry. This is something we get asked for occasionally, but we have a lot of higher priorities at the moment. If you want to vote for this feature, please email us at firstname.lastname@example.org.
In terms of specific timing:
As of the end of 2017, we have no plan to add AsciiDoc in the next 6 months. However, we may consider adding it in future after our Markua support is fully complete. So, if you want us to consider it for our late 2018 priorities, emailing email@example.com is the best way to encourage us to do so :)