edit readme

README.md

@@ -29,10 +29,18 @@ The stable release in different languages is published at the link below:
  - [English](https://italia.github.io/eidas-it-wallet-docs/en)
  - [Italian](https://italia.github.io/eidas-it-wallet-docs/it)
 
+### Preview of a branch
+
 Preview of other branches can be navigated by adding the branch name in the webpath, as follows:
 
  - https://italia.github.io/eidas-it-wallet-docs/trust-model/en
 
+### Preview of released versions
+
+Released versions can be navigated by adding the tag in the webpath leaded by a _v_, as follows:
+
+ - https://italia.github.io/eidas-it-wallet-docs/v0.4.0/en
+
 
 ## Documentation
 
@@ -74,6 +82,8 @@ Furthermore, this project uses the git *branches* and *tags* in the following wa
 * The [release page](https://github.com/italia/publiccode.yml/releases) of
   GitHub contains all the released versions of the standard. For the sake of coherence, the *releases* are made according to the tag names.
 
+Each time a release is created or edited, a preview is built based on the tag the release refers to. See [the preview section](preview-of-released-versions) for more.
+
 ## How to contribute
 
 Feel free to open [Pull Requests and to present a problem with an Issue](CONTRIBUTING.md).