Clarify documentation for accountPatchReviewDb.url

Change-Id: I370589a07118fc32393ed3375e93308729c1bf98
diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index 0a28534..dd2745b 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -31,8 +31,8 @@
 Default is to create H2 database in the db folder of the site path.
 +
 Changing this parameter requires to migrate database using the
-link:pgm-MigrateAccountPatchReviewDb.html[MigrateAccountPatchReviewDb program]
-before restarting the Gerrit server.
+link:pgm-MigrateAccountPatchReviewDb.html[MigrateAccountPatchReviewDb] program.
+Migration cannot be done while the server is running.
 
 ----
 [accountPatchReviewDb]