fix for maven build Error message on windows

[ERROR] OS=Windows and the assembly descriptor contains a *nix-specific root-relative-reference (starting with slash) /

Signed-off-by: qxo <qxodream@gmail.com>

src/main/assembly/docs.xml

@@ -9,7 +9,7 @@
   <fileSets>
     <fileSet>
       <directory>${project.build.directory}/asciidoc</directory>
-      <outputDirectory>/</outputDirectory>
+      <outputDirectory>./</outputDirectory>
     </fileSet>
   </fileSets>
 </assembly>