Update trellis-doc publishing job

Also install `enchant` so spellchecking works in Sphinx

Change-Id: I990454bf061f583657181fcd3094542a4f97965c
diff --git a/jjb/repos/trellis-docs.yaml b/jjb/repos/trellis-docs.yaml
index 9bd917c..ac37972 100644
--- a/jjb/repos/trellis-docs.yaml
+++ b/jjb/repos/trellis-docs.yaml
@@ -26,7 +26,7 @@
       - 'version-tag'
       - 'sync-dir':
           dependency-jobs: 'version-tag_trellis-docs'
-          build-command: 'make html'
-          build-output-path: '_build/html/'
+          build-command: 'make multiversion'
+          build-output-path: '_build/multiversion/'
           sync-target-server: 'guide.opencord.org'
           sync-target-path: '/var/www/trellis-docs/'