Bug#850387: spring: Move from asciidoc to asciidoc-base as build dependency

[Joseph Herlant]

Package: spring
Severity: wishlist

Dear Maintainer,

Asciidoc has been split in different packages in #637006 and #729242.
This split has arrived in Testing.

To lower the number of dependencies to install during the build, could
you evaluate the switch of the build-depends from asciidoc to
asciidoc-base instead of asciidoc please?

asciidoc-base is enough to build manpages and html pages.

Thanks for your help,
Joseph