Improve readme

Signed-off-by: Michal Čihař <michal@cihar.com>

README.md

@@ -4,6 +4,9 @@ Run phpMyAdmin with Alpine and PHP built in web server.
 
 [![Build Status](https://travis-ci.org/phpmyadmin/docker.svg?branch=master)](https://travis-ci.org/phpmyadmin/docker)
 
+All following examples will bring you phpMyAdmin on `http://localhost:8080`
+where you can enjoy your happy MySQL administration.
+
 
 ## Usage with linked server
 
@@ -14,10 +17,6 @@ link a running mysql instance container:
 docker run --name myadmin -d --link mysql_db_server:db -p 8080:8080 phpmyadmin/phpmyadmin
 ```
 
-Then open browser, visit http://***.***.host.ip:8080
-
-You will see the phpMyAdmin login page.
-
 ## Usage with external server
 
 You can specify MySQL host in the `PMA_HOST` environment variable. You can also
@@ -27,13 +26,9 @@ use `PMA_PORT` to specify port of the server in case it's not the default one:
 docker run --name myadmin -d -e PMA_HOST=dbhost -p 8080:8080 phpmyadmin/phpmyadmin
 ```
 
-Then open browser, visit http://***.***.host.ip:8080
-
-You will see the phpMyAdmin login page.
-
 ## Usage with arbitrary server
 
-You can use arbitrary servers by adding ENV variable PMA\_ARBITRARY=1 to the startup command:
+You can use arbitrary servers by adding ENV variable `PMA_ARBITRARY=1` to the startup command:
 
 ```
 docker run --name myadmin -d --link mysql_db_server:db -p 8080:8080 -e PMA_ARBITRARY=1 phpmyadmin/phpmyadmin
@@ -50,4 +45,8 @@ Using the docker-compose.yml from https://github.com/phpmyadmin/docker
 docker-compose up -d
 ```
 
-than as usual, open http://localhost:8080 and enjoy your happy MySQL administration.
+## Environment variables summary
+
+* ``PMA_ARBITRARY`` - when set to 1 connection to the arbitrary server will be allowed
+* ``PMA_HOST`` - define address/host name of the MySQL server
+* ``PMA_PORT`` - define port of the MySQL server