config-project-config.txt: Fix links to submit.mergeContent option

The file contains links to '#submit.mergeContent' but such an anchor
doesn't exist. The submit.mergeContent does have an anchor but it's
'#content_merge'. To fix the links we add a '#submit.mergeContent'
anchor, because this anchor is consistent with the anchor names of all
other sections.

Release-Notes: skip
Change-Id: Ie7d42ba307534e58fffd77e00afe57673b8e0b8b
Signed-off-by: Edwin Kempin <ekempin@google.com>
diff --git a/Documentation/config-project-config.txt b/Documentation/config-project-config.txt
index 1accef0..218affd 100644
--- a/Documentation/config-project-config.txt
+++ b/Documentation/config-project-config.txt
@@ -317,7 +317,9 @@
 The submit section includes configuration of project-specific
 submit settings:
 
-[[content_merge]]submit.mergeContent::
+[[content_merge]]
+
+[[submit.mergeContent]]submit.mergeContent::
 +
 Defines whether Gerrit will try to do a content merge when a path conflict
 occurs while submitting a change.