docs: restore external links lost in navbar restructure

Add Examples and Rust API as text links in the top navbar via the
pydata-sphinx-theme external_links option. Nest the code-of-conduct
link inside the Contributor Guide toctree so it appears alongside the
other contributor pages. Drop the duplicate "Further reading" bullet
list from the landing page now that every link has a permanent home.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: timsaucer

docs/source/conf.py

@@ -133,6 +133,16 @@ def setup(sphinx) -> None:
             "icon": "fa-brands fa-github",
         },
     ],
+    "external_links": [
+        {
+            "name": "Examples",
+            "url": "https://github.com/apache/datafusion-python/tree/main/examples",
+        },
+        {
+            "name": "Rust API",
+            "url": "https://docs.rs/datafusion/latest/datafusion/",
+        },
+    ],
     "secondary_sidebar_items": [],
     "collapse_navigation": True,
     "show_nav_level": 1,

docs/source/contributor-guide/index.rst

@@ -26,3 +26,4 @@ Guides for contributors to the DataFusion in Python project.
 
    introduction
    ffi
+   Code of Conduct <https://github.com/apache/datafusion/blob/main/CODE_OF_CONDUCT.md>

docs/source/index.rst

@@ -52,14 +52,6 @@ Example
     df.show()
 
 
-Further reading:
-
-* `Examples <https://github.com/apache/datafusion-python/tree/main/examples>`_ — runnable scripts demonstrating common patterns.
-* `GitHub repository and issue tracker <https://github.com/apache/datafusion-python>`_.
-* `Rust API docs <https://docs.rs/datafusion/latest/datafusion/>`_ for the underlying engine.
-* `Apache DataFusion code of conduct <https://github.com/apache/datafusion/blob/main/CODE_OF_CONDUCT.md>`_.
-
-
 .. toctree::
    :hidden:
    :maxdepth: 1