Mark the optional fields of config-info in the REST API documentation

Change-Id: I40c4217e0f4391110ad0f4275d8d41df7c886d3f
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/Documentation/rest-api-projects.txt b/Documentation/rest-api-projects.txt
index 83ef7a9..2a1ca00 100644
--- a/Documentation/rest-api-projects.txt
+++ b/Documentation/rest-api-projects.txt
@@ -1067,33 +1067,33 @@
 Fields marked with * are only visible to users who have read access to
 `refs/meta/config`.
 
-[options="header",width="50%",cols="1,6"]
-|======================================
-|Field Name                   |Description
-|`use_contributor_agreements*`|
+[options="header",width="50%",cols="1,^2,4"]
+|==========================================
+|Field Name                   ||Description
+|`use_contributor_agreements*`|optional|
 link:#inherited-boolean-info[InheritedBooleanInfo] that tells whether
 authors must complete a contributor agreement on the site before
 pushing any commits or changes to this project.
-|`use_content_merge*`|
+|`use_content_merge*`         |optional|
 link:#inherited-boolean-info[InheritedBooleanInfo] that tells whether
 Gerrit will try to perform a 3-way merge of text file content when a
 file has been modified by both the destination branch and the change
 being submitted. This option only takes effect if submit type is not
 FAST_FORWARD_ONLY.
-|`use_signed_off_by*`|
+|`use_signed_off_by*`         |optional|
 link:#inherited-boolean-info[InheritedBooleanInfo] that tells whether
 each change must contain a Signed-off-by line from either the author or
 the uploader in the commit message.
-|`require_change_id*`|
+|`require_change_id*`         |optional|
 link:#inherited-boolean-info[InheritedBooleanInfo] that tells whether a
 valid link:user-changeid.html[Change-Id] footer in any commit uploaded
 for review is required. This does not apply to commits pushed directly
 to a branch or tag.
-|`commentlinks`|
+|`commentlinks`               ||
 Comment link configuration for the project. Has the same format as the
 link:config-gerrit.html#_a_id_commentlink_a_section_commentlink[commentlink section]
 of `gerrit.config`.
-|======================================
+|==========================================
 
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