test sphinx mapping to networkx (#4323)

Closes #4285

I'll report back if it get to render locally. Ran out of mem building the library on my ec2 machine (g5.2xlarge: 32 Gb RAM) but I did just build cudf. I'll try again soon.

~~Also brainstorming here and I probably should upstream this to the rapids CI process. Would be nice to have /ok to test docs which just builds the docs for this PR~~ created nv-gha-runners/nvidia-runners#25

I tried building the docs locally and got

```
WARNING: [autosummary] failed to import cugraph.jaccard_w.
Possible hints:
* AttributeError: module 'cugraph' has no attribute 'jaccard_w'
* ImportError: 
* ModuleNotFoundError: No module named 'cugraph.jaccard_w'
WARNING: [autosummary] failed to import cugraph.overlap_w.
Possible hints:
* ModuleNotFoundError: No module named 'cugraph.overlap_w'
* ImportError: 
* AttributeError: module 'cugraph' has no attribute 'overlap_w'
WARNING: [autosummary] failed to import cugraph.sorensen_w.
Possible hints:
* ModuleNotFoundError: No module named 'cugraph.sorensen_w'
* ImportError: 
* AttributeError: module 'cugraph' has no attribute 'sorensen_w'
```

Think this comes from https://github.com/rapidsai/cugraph/blob/abe69c0419b67b567d3c8fce91ee1a062d53e385/docs/cugraph/source/api_docs/cugraph/link_prediction.rst#L14

but I may have messed up my build

Authors:
  - Ray Bell (https://github.com/raybellwaves)
  - Rick Ratzel (https://github.com/rlratzel)

Approvers:
  - Rick Ratzel (https://github.com/rlratzel)

URL: #4323

docs/cugraph/source/conf.py

@@ -190,9 +190,17 @@
      'Miscellaneous'),
 ]
 
-# Example configuration for intersphinx: refer to the Python standard library.
-intersphinx_mapping = {'https://docs.python.org/': None}
-
+# Connect docs in other projects
+intersphinx_mapping = {
+    "networkx": (
+        "https://networkx.org/documentation/stable/",
+        "https://networkx.org/documentation/stable/objects.inv",
+    ),
+    "python": (
+        "https://docs.python.org/3",
+        "https://docs.python.org/3/objects.inv",
+    ),
+}
 
 # Config numpydoc
 numpydoc_show_inherited_class_members = False

python/cugraph/cugraph/structure/convert_matrix.py

@@ -1,4 +1,4 @@
-# Copyright (c) 2019-2023, NVIDIA CORPORATION.
+# Copyright (c) 2019-2024, NVIDIA CORPORATION.
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
 # You may obtain a copy of the License at
@@ -277,6 +277,8 @@ def from_pandas_edgelist(
     renumber=True,
 ):
     """
+    See :func:`networkx.convert_matrix.from_pandas_edgelist`.
+
     Initialize a graph from the edge list. It is an error to call this
     method on an initialized Graph object. Source argument is source
     column name and destination argument is destination column name.