Move urgent PR merge docs to end of contributing guide

Keep the committer-only procedure out of the contributor setup flow, and
indent the code block 4 spaces so mkdocs renders it inside the list.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: kevinjqliu

mkdocs/docs/contributing.md

@@ -263,20 +263,6 @@ This command spins up the full integration test infrastructure via Docker Compos
 
 After running `make notebook-infra`, open `spark_integration_example.ipynb` in the Jupyter Lab interface to explore Spark integration capabilities.
 
-## Merging an urgent PR
-
-Committers can merge an urgent, approved pull request without waiting for the merge queue or required checks (for example, a security fix while CI is stuck). Use this only when necessary; otherwise, let the merge queue run.
-
-<!-- markdown-link-check-disable-next-line -->
-1. Join the [`apache/iceberg-public`](https://github.com/orgs/apache/teams/iceberg-public) team via [Boxer](https://gitbox.apache.org/boxer/) (one-time; membership syncs in about 15 minutes).
-2. Get the pull request approved by a committer.
-3. If the pull request is in the merge queue, click **Remove from queue**.
-4. Merge it directly:
-
-   ```sh
-   gh pr merge <number> --squash --admin
-   ```
-
 ## Code standards
 
 Below are the formalized conventions that we adhere to in the PyIceberg project. The goal of this is to have a common agreement on how to evolve the codebase, but also using it as guidelines for newcomers to the project.
@@ -352,3 +338,17 @@ For the type annotation the types from the `Typing` package are used.
 ### Third party libraries
 
 PyIceberg naturally integrates into the rich Python ecosystem, however it is important to be hesitant adding third party packages. Adding a lot of packages makes the library heavyweight, and causes incompatibilities with other projects if they use a different version of the library. Also, big libraries such as `s3fs`, `adlfs`, `pyarrow`, `thrift` should be optional to avoid downloading everything, while not being sure if is actually being used.
+
+## Merging an urgent PR
+
+Committers can merge an urgent, approved pull request without waiting for the merge queue or required checks (for example, a security fix while CI is stuck). Use this only when necessary; otherwise, let the merge queue run.
+
+<!-- markdown-link-check-disable-next-line -->
+1. Join the [`apache/iceberg-public`](https://github.com/orgs/apache/teams/iceberg-public) team via [Boxer](https://gitbox.apache.org/boxer/) (one-time; membership syncs in about 15 minutes).
+2. Get the pull request approved by a committer.
+3. If the pull request is in the merge queue, click **Remove from queue**.
+4. Merge it directly:
+
+    ```sh
+    gh pr merge <number> --squash --admin
+    ```