Fix the location of the issue-state-transition.config in the docs

From the source code [1] it is obvious that this file should be created
under $GERRIT_SITE/etc/ and not directly under the $GERRIT_SITE.

[1] https://gerrit.googlesource.com/plugins/hooks-its/+/master/hooks-its/src/main/java/com/googlesource/gerrit/plugins/hooks/workflow/GerritHookFilterChangeState.java

Change-Id: I0eaefd4d6bdbcd1a91aa07d44eb371522f233003

src/main/resources/Documentation/config.md

diff --git a/src/main/resources/Documentation/config.md b/src/main/resources/Documentation/config.md
index 646cec8..93e0774 100644
--- a/src/main/resources/Documentation/config.md
+++ b/src/main/resources/Documentation/config.md
@@ -96,7 +96,8 @@
 Jira plugin is able to automate status transition on the issues based on
 code-review actions performed on Gerrit; actions are performed on Jira using
 the username/password provided during Gerrit init.
-Transition automation is driven by `$GERRIT_SITE/issue-state-transition.config` file.
+Transition automation is driven by `$GERRIT_SITE/etc/issue-state-transition.config`
+file.
 
 Syntax of the status transition configuration file is the following: