Remove the section on the changelog from the README

It was redundant with instructions from the wiki page on releasing.

Author: elia

lib/solidus_dev_support/templates/extension/README.md

@@ -71,20 +71,9 @@ $ bin/rails server
 Use Ctrl-C to stop
 ```
 
-### Updating the changelog
-
-Before and after releases the changelog should be updated to reflect the up-to-date status of
-the project:
-
-```shell
-bin/rake changelog
-git add CHANGELOG.md
-git commit -m "Update the changelog"
-```
-
 ### Releasing new versions
 
-Please refer to the dedicated [page](https://github.com/solidusio/solidus/wiki/How-to-release-extensions) on Solidus wiki.
+Please refer to the [dedicated page](https://github.com/solidusio/solidus/wiki/How-to-release-extensions) in the Solidus wiki.
 
 ## License