Merge pull request #1407 from jhatherill/patch-12

Update SUMMARY.md

Author: emmauhl

coalition-publica/en/SUMMARY.md

@@ -6,3 +6,4 @@
    * [Site Administrator Steps](./initial-setup.md#site-admin)
    * [System Administrator Steps](./initial-setup.md#sys-admin)
 * [Subscriptions and Non-Publishing Use of OJS](./subscriptions.md)
+* [Troubleshooting](./troubleshooting.md)