Fix synopsis in replication start cmd documentation

--url is usable with --all or projects and on its own. Update the
usage to reflect this.

Change-Id: Id3637f7bf61b7f65348b19ec0616808ef3f44ccf
diff --git a/src/main/resources/Documentation/cmd-start.md b/src/main/resources/Documentation/cmd-start.md
index 8291421..e12ec92 100644
--- a/src/main/resources/Documentation/cmd-start.md
+++ b/src/main/resources/Documentation/cmd-start.md
@@ -11,8 +11,7 @@
 ssh -p @SSH_PORT@ @SSH_HOST@ @PLUGIN@ start
   [--now]
   [--wait]
-  [--url <PATTERN>]
-  {--all | <PROJECT PATTERN> ...}
+  {--url <PATTERN> | [--url <PATTERN>] --all | [--url <PATTERN>] <PROJECT PATTERN> ...}
 ```
 
 DESCRIPTION