Remove references to ReviewDb in README.md

Gerrit doesn't have ReviewDb anymore from v3.0 onwards
and therefore any reference to it from the highavailability
plugin README.md would be misleading for the reader.

Change-Id: I727ca716d7a34ba404d42d50ab5578e8681cc722
diff --git a/README.md b/README.md
index 8e7ef27..c8ac4b4 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,12 @@
 # Gerrit high-availability plugin
 
 This plugin allows deploying a cluster of multiple Gerrit masters
-on the same data-center sharing the same ReviewDb and Git repositories.
+on the same data-center sharing the same Git repositories.
 
 Requirements for the Gerrit masters are:
 
 - Gerrit v2.14.20 or later
 - Externally mounted filesystem shared among the cluster
-- ReviewDb on an external DataBase Server
 - Load-balancer (HAProxy or similar)
 
 ## License
@@ -25,12 +24,12 @@
 `gerrit-02.mycompany.com`, listening on the HTTP port 8080, with a shared volume
 mounted under `/shared`, see below the minimal configuration steps.
 
-1. Install one Gerrit master on the first node (e.g. `gerrit-01.mycompany.com`) using an external
-   ReviewDb on a DB server and the repositories location under the shared volume (e.g. `/shared/git`).
-   Init the site in order to create the DB Schema and the initial repositories.
+1. Install one Gerrit master on the first node (e.g. `gerrit-01.mycompany.com`)
+   with the repositories location under the shared volume (e.g. `/shared/git`).
+   Init the site in order to create the initial repositories.
 
 2. Copy all the files of the first Gerrit master onto the second node (e.g. `gerrit-02.mycompany.com`)
-   so that it points to the same ReviewDb and the same repositories location.
+   so that it points to the same repositories location.
 
 3. Install the high-availability plugin into the `$GERRIT_SITE/plugins` directory of both
    the Gerrit servers.