Update README.md instructions for Gerrit v3.3

Align the instructions on how to use the Gerrit docker image
for the new v3.3 version, leveraging the new entrypoint argument
features and removing the redundant canonicalWebUrl setting.

Change-Id: I7b78c6f4811c2580bcdcf1af687c3b28ed5d0394
diff --git a/README.md b/README.md
index 736ae89..dd72e68 100644
--- a/README.md
+++ b/README.md
@@ -25,21 +25,21 @@
 Starting from Ver. 2.14, a new introduction screen guides you through the basics of Gerrit
 and allows installing additional plugins downloaded from [Gerrit CI](https://gerrit-ci.gerritforge.com).
 
-Official releases are also available as Docker images, e.g. use the following to run the 3.2.3 version.
+Official releases are also available as Docker images, e.g. use the following to run the 3.3.0 version.
 
 ```
-docker run -ti -p 8080:8080 -p 29418:29418 gerritcodereview/gerrit:3.2.3
+docker run -ti -p 8080:8080 -p 29418:29418 gerritcodereview/gerrit:3.3.0
 ```
 
 ## Build docker image
 
 For docker images that contain released Gerrit versions, tags exist in this git repository pointing
-to a state of the repository, where this version of Gerrit (e.g. 3.2.3) is referenced in the
+to a state of the repository, where this version of Gerrit (e.g. 3.3.0) is referenced in the
 Dockerfiles. To build such a docker image for development purposes, checkout the respective version
 tag, e.g.:
 
 ```
-git checkout v3.2.3
+git checkout v3.3.0
 ```
 
 Navigate to either `./centos/8` or `./ubuntu/20` to build the centos- or ubuntu-based docker image,
@@ -130,7 +130,7 @@
       - /external/gerrit/cache:/var/gerrit/cache
     environment:
       - CANONICAL_WEB_URL=http://localhost
-    # entrypoint: /entrypoint.sh init
+    # command: init
 
   ldap:
     image: osixia/openldap
@@ -156,7 +156,6 @@
 ```
 [gerrit]
   basePath = git
-  canonicalWebUrl = http://localhost
 
 [index]
   type = LUCENE
@@ -205,7 +204,7 @@
 
 #### Step-1: Run Gerrit docker init setup from docker
 
-Uncomment in docker-compose.yaml the Gerrit init step entrypoint and run Gerrit with docker-compose
+Uncomment the `command: init` option in docker-compose.yaml and run Gerrit with docker-compose
 in foreground.
 
 ```
@@ -217,7 +216,7 @@
 
 #### Step-2: Start Gerrit in daemon mode
 
-Comment out the gerrit init entrypoint in docker-compose.yaml and start all the docker-compose nodes:
+Comment out the `command: init` option in docker-compose.yaml and start all the docker-compose nodes:
 
 ```
 docker-compose up -d