[cli-ref] add rmdir to cleanup working directory

Change-Id: I40deb83f849782cb9f68d695c14643c4fa89aca6

bin/doc-tools-update-cli-reference

@@ -89,6 +89,7 @@ branch=cli-reference
 git branch --list $branch && git branch -D $branch
 git checkout -b $branch
 mv ../output/${project}.rst "doc/cli-reference/source"
+rm -rf ../output
 version=$($project --version 2>&1)
 version=${version##*\)}
 git commit -a -m "[cli-ref] Update python-${project}client to ${version##* }"