chore: correct tag in pom.xml

Needs to be HEAD for everything but the tagged commit.

Author: line-o

pom.xml

@@ -36,7 +36,7 @@
         <url>https://www.github.com/exist-db/function-documentation.git</url>
         <connection>scm:git:https://www.github.com/exist-db/function-documentation.git</connection>
         <developerConnection>scm:git:https://www.github.com/exist-db/function-documentation.git</developerConnection>
-      <tag>2.0.0</tag>
+        <tag>HEAD</tag>
   </scm>
     <issueManagement>
         <system>GitHub</system>