Bump asciidoctor-maven-plugin from 2.1.0 to 2.2.1 (#600)

Bumps [asciidoctor-maven-plugin](https://github.com/asciidoctor/asciidoctor-maven-plugin) from 2.1.0 to 2.2.1.
- [Release notes](https://github.com/asciidoctor/asciidoctor-maven-plugin/releases)
- [Changelog](https://github.com/asciidoctor/asciidoctor-maven-plugin/blob/main/CHANGELOG.adoc)
- [Commits](asciidoctor/asciidoctor-maven-plugin@asciidoctor-maven-plugin-2.1.0...2.2.1)

---
updated-dependencies:
- dependency-name: org.asciidoctor:asciidoctor-maven-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pom.xml

@@ -280,7 +280,7 @@ Integrates with Spring Data, Spring Data REST and Apache Solr</description>
                     <plugin>
                         <groupId>org.asciidoctor</groupId>
                         <artifactId>asciidoctor-maven-plugin</artifactId>
-                        <version>2.1.0</version>
+                        <version>2.2.1</version>
                         <configuration>
                             <backend>html</backend>
                             <doctype>book</doctype>