Adding CAGRA merge to the documentation (#1942)

Closes #1787.

Authors:
  - Victor Lafargue (https://github.com/viclafargue)
  - Corey J. Nolet (https://github.com/cjnolet)
  - Anupam (https://github.com/aamijar)

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

URL: #1942

Author: viclafargue

c/include/cuvs/neighbors/cagra.h

@@ -827,6 +827,15 @@ cuvsError_t cuvsCagraIndexFromArgs(cuvsResources_t res,
                                    DLManagedTensor* dataset,
                                    cuvsCagraIndex_t index);
 
+/**
+ * @}
+ */
+
+/**
+ * @defgroup cagra_c_index_merge CAGRA C-API merge functions
+ * @{
+ */
+
 /**
  * @brief Merge multiple CAGRA indices into a single CAGRA index.
  *

docs/source/c_api/neighbors_cagra_c.rst

@@ -50,6 +50,14 @@ Index search
     :members:
     :content-only:
 
+Index merge
+-----------
+
+.. doxygengroup:: cagra_c_index_merge
+    :project: cuvs
+    :members:
+    :content-only:
+
 Index serialize
 ---------------
 

docs/source/cpp_api/neighbors_cagra.rst

@@ -67,6 +67,14 @@ Index extend
     :members:
     :content-only:
 
+Index merge
+-----------
+
+.. doxygengroup:: cagra_cpp_index_merge
+    :project: cuvs
+    :members:
+    :content-only:
+
 Index serialize
 ---------------