docs: Run Notebook files converted to *.py files under tutorials (#729)

Author: DeaMariaLeon

ci/test_examples.sh

@@ -1,3 +1,3 @@
-for example in $(find ./examples/ -iname *.py); do
+for example in $(find ./examples/ -iname *.py) $(find ./docs/examples/ -iname *.py); do
   CI_MODE=1 python $example
 done

docs/examples/finch_example.py

@@ -0,0 +1,42 @@
+# ---
+# jupyter:
+#   jupytext:
+#     text_representation:
+#       extension: .py
+#       format_name: light
+#       format_version: '1.5'
+#       jupytext_version: 1.16.3
+#   kernelspec:
+#     display_name: sparse
+#     language: python
+#     name: python3
+# ---
+
+# ## Import
+# Let's set the backend and import `sparse`.
+
+# +
+import os
+
+os.environ["SPARSE_BACKEND"] = "Finch"
+
+import sparse
+
+import numpy as np
+
+# -
+
+# ## Perform Operations
+# Let's create two arrays.
+
+rng = np.random.default_rng(42)  # Seed for reproducibility
+a = sparse.random((3, 3), density=1 / 6, random_state=rng)
+b = sparse.random((3, 3), density=1 / 6, random_state=rng)
+
+# Now let's matrix multiply them.
+
+c = a @ b
+
+# And view the result as a (dense) NumPy array.
+
+c.todense()