[Release] Remove release process doc (#19312)

Author: jjyao

doc/source/installation.rst

@@ -9,7 +9,7 @@ Windows wheels are now available, but :ref:`Windows support <windows-support>` i
 Official Releases
 -----------------
 
-You can install the latest official version of Ray as follows. Official releases are produced according to the `release process doc <https://github.com/ray-project/ray/blob/master/release/RELEASE_PROCESS.rst>`__.
+You can install the latest official version of Ray as follows.
 
 .. code-block:: bash
 

release/README.md

@@ -0,0 +1,2 @@
+# Release Tests
+While the exact release process relies on Anyscale internal tooling, the tests we run during the releases are located at <https://github.com/ray-project/ray/blob/master/release/.buildkite/build_pipeline.py>