Site/contributing: add recommendations for working with PRs (#1625)

This change updates the PR guidelines on the "Contributing" web page after [this discussion](https://lists.apache.org/thread/kfxo3cqmw3pgrpgtgqvqpwvn46yw8q7h).

Also adopt `gradlew test` to `gradlew check` in README, following the intent (all tests, incl ITs)

Author: snazy

CONTRIBUTING.md

@@ -64,32 +64,60 @@ Before starting on a large code change, please describe the concept/design of wh
 
 The best way to provide changes is to fork Apache Polaris repository on GitHub and provide a Pull Request with your changes. To make it easy to apply your changes please use the following conventions:
 
-* Every Pull Request should have a matching GitHub Issue.
-* Create a branch that will house your change:
-
-```bash
-git clone https://github.com/apache/polaris
-cd polaris
-git fetch --all
-git checkout -b my-branch origin/main
-```
-
-  Don't forget to periodically rebase your branch:
-
-```bash
-git pull --rebase
-git push GitHubUser my-branch --force
-```
-
-  Ensure the code is properly formatted:
-
-```bash
-./gradlew format
-```
+#### Before opening a pull request
 
 * Pull Requests should be based on the `main` branch.
-* Test that your changes works by adapting or adding tests. Verify the build passes (see `README.md` for build instructions).
+* Create a branch that will house your change:
+  ```bash
+  git clone https://github.com/apache/polaris
+  cd polaris
+  git checkout main
+  git pull
+  git checkout -b my-branch
+  ```
+* Work on the changes of your pull requests locally.
+* Recommended checks:
+  ```bash
+  # Ensure the code is properly formatted and compiles:
+  ./gradlew format compileAll
+  # Ensure the code is passing the checks (including formatting checks & tests):
+  ./gradlew check
+  ```
+* You may want to push your changes to your personal Polaris fork. Git will emit a URL that you can use to create the Pull Request. Do not create the Pull Request yet.
+  ```bash
+  git push --set-upstream your-github-accout
+  ```
+
+#### Opening a Pull Request
+
+* The Pull Request summary should provide a concise summary of the change, get inspired by [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/).
+* The Pull Request description should provide the background (rationale) of the change and describe the changes in way that someone who has no prior knowledge can understand the rationale of the change and the change itself.
+* If there is a matching GitHub Issue, add a separate line at the end of the commit message of the issue that the PR fixes. Do not add the issue number into the subject.
+  ```
+  Fixes #123456
+  ```
+  If the PR does not fully fix the issue, use `Related to #123456` instead of `Fixes #123456`.
+
+Tips:
+* If the branch for your Pull Request contains only one (squashed) commit, GitHub will populate the PR summary and description from that single commit.
+* When opening a PR consider whether the PR is "draft" or already "ready for review". "Draft" means work in progress, things will change, but comments are welcome. "Ready for review" means that the PR is requested to be merged as is (pending review feedback).
+
+#### Working on a Pull Request
+
+* Don't forget to periodically rebase your branch:
+  ```bash
+  git pull --rebase
+  git push your-github-accout my-branch --force
+  ```
+* Test that your changes work by adapting or adding tests. Verify the build passes (see `README.md` for build instructions).
 * If your Pull Request has conflicts with the `main` branch, please rebase and fix the conflicts.
+* If your PR requires more work or time or bigger changes, please put the PR to "draft" state to indicate that it is not meant to be "thoroughly" reviewed at this point.
+
+#### Merging a Pull Request
+
+* When a PR is about to be merged, cross-check the commit summary and message for the merged Git commit.
+* Keep in mind that the Git commit subject and message is going to be read by other people, potentially even after years. The Git commit subject and message will appear "as is" in release notes.
+* Make sure the subject and message are properly formatted and contains a concise description of the changes in way that someone who has no prior knowledge can understand the rationale of the change and the change itself. Remove information that's of no use for someone reading the Git commit log, for example single intermediate commit messages like `formatting` or `fix test`.
 
 ## Java version requirements
 

README.md

@@ -67,7 +67,7 @@ Apache Polaris is built using Gradle with Java 21+ and Docker 27+.
 
 - `./gradlew build` - To build and run tests. Make sure Docker is running, as the integration tests depend on it.
 - `./gradlew assemble` - To skip tests.
-- `./gradlew test` - To run unit tests and integration tests.
+- `./gradlew check` - To run all checks, including unit tests and integration tests.
 - `./gradlew run` - To run the Polaris server locally; the server is reachable at localhost:8181. This is also suitable for running regression tests, or for connecting with Spark. Set your own credentials by specifying system property `./gradlew run -Dpolaris.bootstrap.credentials=POLARIS,root,secret` where:
   - `POLARIS` is the realm
   - `root` is the CLIENT_ID