Add Cluster and Distance sections to C documentation (#1955)

They are currently not documented.

Authors:
  - Micka (https://github.com/lowener)
  - Corey J. Nolet (https://github.com/cjnolet)
  - Anupam (https://github.com/aamijar)

Approvers:
  - Corey J. Nolet (https://github.com/cjnolet)

URL: #1955

Author: lowener

c/include/cuvs/distance/pairwise_distance.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: Copyright (c) 2024, NVIDIA CORPORATION.
+ * SPDX-FileCopyrightText: Copyright (c) 2024-2026, NVIDIA CORPORATION.
  * SPDX-License-Identifier: Apache-2.0
  */
 #pragma once
@@ -12,6 +12,11 @@
 extern "C" {
 #endif
 
+/**
+ * @defgroup pairwise_distance_c C pairwise distance
+ * @{
+ */
+
 /**
  * @brief Compute pairwise distances for two matrices
  *
@@ -46,6 +51,9 @@ cuvsError_t cuvsPairwiseDistance(cuvsResources_t res,
                                  DLManagedTensor* dist,
                                  cuvsDistanceType metric,
                                  float metric_arg);
+
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif

docs/source/c_api.rst

@@ -8,5 +8,7 @@ C API Documentation
    :maxdepth: 4
 
    c_api/core_c_api.rst
+   c_api/distance.rst
+   c_api/cluster.rst
    c_api/neighbors.rst
    c_api/preprocessing.rst

docs/source/c_api/cluster.rst

@@ -0,0 +1,12 @@
+Clustering
+==========
+
+.. role:: py(code)
+   :language: c
+   :class: highlight
+
+.. toctree::
+   :maxdepth: 2
+   :caption: Contents:
+
+   cluster_kmeans_c.rst

docs/source/c_api/cluster_kmeans_c.rst

@@ -0,0 +1,27 @@
+K-Means
+=======
+
+.. role:: py(code)
+   :language: c
+   :class: highlight
+
+Parameters
+----------
+
+``#include <cuvs/cluster/kmeans.h>``
+
+.. doxygengroup:: kmeans_c_params
+   :project: cuvs
+   :members:
+   :content-only:
+
+
+Functions
+---------
+
+``#include <cuvs/cluster/kmeans.h>``
+
+.. doxygengroup:: kmeans_c
+   :project: cuvs
+   :members:
+   :content-only:

docs/source/c_api/distance.rst

@@ -0,0 +1,26 @@
+Distance
+========
+
+.. role:: py(code)
+   :language: c
+   :class: highlight
+
+
+Distance types
+--------------
+
+``#include <cuvs/distance/distance.h>``
+
+.. doxygenenum:: cuvsDistanceType
+   :project: cuvs
+
+
+Pairwise distance
+-----------------
+
+``#include <cuvs/distance/pairwise_distance.h>``
+
+.. doxygengroup:: pairwise_distance_c
+   :project: cuvs
+   :members:
+   :content-only: