Update integration tests related documentation for better clarity (ap…

…ache#16313)

integration-tests-ex/README.md

@@ -42,13 +42,20 @@ an explanation.
 ./it.sh image
 ```
 
+Note: If you are running it on Apple Silicon processors, you would also need to uncomment all occurrences of `platform: linux/x86_64` in [dependencies.yaml](https://github.com/apache/druid/blob/master/integration-tests-ex/cases/cluster/Common/dependencies.yaml).
+
 ### Run an IT from the Command Line
 
 ```bash
 ./it.sh test <category>
 ```
 
-Where `<category>` is one of the test categories.
+Where `<category>` is one of the test categories. You can see the list of test categories at [`src/test/java/org/apache/druid/testsEx/categories`](https://github.com/apache/druid/tree/master/integration-tests-ex/cases/src/test/java/org/apache/druid/testsEx/categories). The corresponding test classes are also annotated with `@Category` like `@Category(HighAvailability.class)`.
+
+For example, a sample command for running IT for `@Category(HighAvailability.class)` would be:
+```bash
+./it.sh test HighAvailability
+```
 
 ### Run an IT from the IDE
 

integration-tests/README.md

@@ -57,7 +57,7 @@ export APACHE_ARCHIVE_MIRROR_HOST=https://example.com/remote-generic-repo
 This section describes how to start integration tests against Docker containers which will be brought up automatically by following commands.
 If you want to build Docker images and run tests separately, see the next section.
 
-To run all tests from a test group using Docker and Maven run the following command:
+To run all tests from a test group using Docker and Maven run the following command from `integration-tests` directory:
 
 ```bash
 mvn verify -P integration-tests -Dgroups=<test_group>
@@ -68,7 +68,7 @@ The list of test groups can be found at
 
 ### Run a single test
 
-To run only a single test using Maven:
+To run only a single test using Maven, run the following command from `integration-tests` directory:
 
 ```bash
 mvn verify -P integration-tests -Dgroups=<test_group> -Dit.test=<test_name>