Suppress myst warnings, remove external links

docs/conf.py

@@ -103,7 +103,7 @@
 exclude_patterns = ["_build", "Thumbs.db", ".DS_Store", ".ipynb_checkpoints"]
 
 # Suppress warnings generated by Sphinx and/or by Sphinx extensions
-suppress_warnings = ["git.too_shallow"]
+suppress_warnings = ["git.too_shallow", "myst.xref_missing"]
 
 # -- Options for HTML output -------------------------------------------------
 
@@ -142,12 +142,6 @@
         },
     ],
     "collapse_navigation": True,
-    "external_links": [
-        {
-            "name": "Contributing",
-            "url": "https://github.com/pybamm-team/PyBaMM/tree/develop/CONTRIBUTING.md",
-        },
-    ],
     # should be kept versioned to use for the version warning bar
     "switcher": {
         "version_match": version,