From now on AsciiDoc3 comes to you under the GNU Affero General Public License Version 3 or later/higher.
Legacy AsciiDoc is/was licensed under GPLv2 or higher. To ensure the highest possible protection against whatever may be or happen we upgrade to the AGPLv3+. This is covered by the classification of the Free Software Foundation and in addition recommended.
See here: https://www.gnu.org/licenses/rms-why-gplv3.html or here https://www.gnu.org/licenses/gpl-faq.html#AllCompatibility or https://opensource.stackexchange.com/questions/6816/gplv2-or-later-upgrade-to-agplv3
To obtain the closing GPLv2+ version, you may checkout the tag v3.2.3a=GPLv2+_vs_AGPLv3+.

Keywords: AsciiDoc3 license GPLv2+ AGPLv3+