[AIR] Add AIR install extra (#24701)

Closes #23439

doc/source/ray-air/getting-started.rst

@@ -16,6 +16,7 @@ Ray AIR consists of 5 key components -- Data processing (Ray Data), Model Traini
 
 Users can use these libraries interchangeably to scale different parts of standard ML workflows.
 
+To get started, install Ray AIR via `pip install -U "ray[air]"`
 
 .. tip::
     **Getting involved with Ray AIR.** We'll be holding office hours, development sprints, and other activities as we get closer to the Ray AIR Beta/GA release. Want to join us? Fill out `this short form <https://forms.gle/wCCdbaQDtgErYycT6>`__!

doc/source/ray-overview/installation.rst

@@ -22,6 +22,7 @@ To install Ray libraries:
 
 .. code-block:: bash
 
+  pip install -U "ray[air]" # installs Ray + dependencies for Ray AI Runtime
   pip install -U "ray[tune]"  # installs Ray + dependencies for Ray Tune
   pip install -U "ray[rllib]"  # installs Ray + dependencies for Ray RLlib
   pip install -U "ray[serve]"  # installs Ray + dependencies for Ray Serve

python/setup.py

@@ -255,6 +255,15 @@ if setup_spec.type == SetupType.RAY:
         "scipy",
     ]
 
+    # Ray AI Runtime should encompass Data, Tune, and Serve.
+    setup_spec.extras["air"] = list(
+        set(
+            setup_spec.extras["tune"]
+            + setup_spec.extras["data"]
+            + setup_spec.extras["serve"]
+        )
+    )
+
     setup_spec.extras["all"] = list(
         set(chain.from_iterable(setup_spec.extras.values()))
     )