Document for MPR should be updated to the latest 14.x

[jcgueriaud1]

Currently the step by step migration guide is using Vaadin 14.0.0.

It also requires an old version of flow-maven-plugin (2.0.7) and there is no explanation how to find the corresponding version for Vaadin 14.x.

The only instruction is inside a comment of the example pom.xml The Flow version to use can be checked from vaadin-bom. without additional information

[jcgueriaud1]

One solution is to get this information here: https://mvnrepository.com/artifact/com.vaadin/vaadin-bom/14.3.1
and change the version.
And check the flow version --> 2.3.1