SONARJAVA-4200 Fixes from review

* Replace reference to SQ version with release season
* Replace "checks" with "rules"
* Link to custom rules

sonar-java-plugin/src/main/resources/static/documentation.md

@@ -73,14 +73,14 @@ If needed, it is possible to run the parsing file by file by setting `sonar.java
 More details can be found [here](https://github.com/SonarSource/sonar-java/wiki/Batch-mode).
 
 ## Skipping unchanged files
-Starting with SonarQube 9.4, and by default, the Java analyzer optimizes the analysis of unchanged files in pull requests.
-In practice, this means that on a file that has not changed, the analyzer only runs a restricted list of checks.
+Starting from April 2022, and by default, the Java analyzer optimizes the analysis of unchanged files in pull requests.
+In practice, this means that on a file that has not changed, the analyzer only runs a restricted list of rules.
 To get a better understanding of the rule exclusion mechanism, keep in mind that:
 * Rules that need to run on multiple files to decide whether they need to raise issues are always executed
 * Rules that need to run at the end of the analysis to decide whether they need to raise issues are always executed
 * Rules that are defined out of the `sonar.java.checks` package are always executed
 
-This last criteria implies that checks defined in custom plugins cannot be skipped.
+This last criteria implies that [custom rules](https://redirect.sonarsource.com/doc/java-custom-rules-guide.html) cannot be skipped.
 
 If you wish to disable this optimization, you can set the value of the analysis parameter `sonar.java.skipUnchanged` to `false`.
 Leaving the parameter untouched is equivalent to having `sonar.java.skipUnchanged` set to `true`.