Improve the documentation for local builds

It is not immediately clear where -DskipTests must be specified. Since
full-build.sh supports the --no-tests argument, advise developers to use
that.

Signed-off-by: Tommaso Fonda <tfonda@fbk.eu>

CONTRIBUTING.md

@@ -73,7 +73,7 @@ You're a committer if you have write-access to the Xtext git-repositories.
  10. If the reviewer approves, merge.
 
 ## Create a Release Locally
- 1. Run the Maven build locally by calling the shell script [`full-build.sh`](https://github.com/eclipse/xtext/blob/main/full-build.sh). You may want to pass `-DskipTests` to skip all tests (keep in mind that with tests the build might take more than 1 hour).
+ 1. Run the Maven build locally by calling the shell script [`full-build.sh`](https://github.com/eclipse/xtext/blob/main/full-build.sh). You may want to pass `--no-tests` to the script to skip all tests (keep in mind that with tests the build might take more than 1 hour).
  2. Find the artifacts at `build/maven-repository` or `build/p2-repository` in a folder relative to the repository root.
 
 ## Consume the Latest Artifacts