cuVS docs updates for release (rapidsai#161)

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

Approvers:
  - Ben Frederickson (https://github.com/benfred)

URL: rapidsai/cuvs#161

cpp/include/cuvs/cluster/agglomerative.hpp

@@ -26,6 +26,11 @@ namespace cuvs::cluster::agglomerative {
 // constant to indirectly control the number of neighbors. k = sqrt(n) + c. default to 15
 constexpr int DEFAULT_CONST_C = 15;
 
+/**
+ * @defgroup agglomerative_params agglomerative clustering hyperparameters
+ * @{
+ */
+
 /**
  * Determines the method for computing the minimum spanning tree (MST)
  */
@@ -45,6 +50,10 @@ enum Linkage {
   KNN_GRAPH = 1
 };
 
+/**
+ * @}
+ */
+
 /**
  * Simple container object for consolidating linkage results. This closely
  * mirrors the trained instance variables populated in
@@ -75,6 +84,10 @@ class single_linkage_output {
   }
 };
 
+/**
+ * @defgroup single_linkage single-linkage clustering APIs
+ * @{
+ */
 /**
  * Single-linkage clustering, capable of constructing a KNN graph to
  * scale the algorithm beyond the n^2 memory consumption of implementations
@@ -105,4 +118,7 @@ void single_linkage(
   cuvs::cluster::agglomerative::Linkage linkage = cuvs::cluster::agglomerative::Linkage::KNN_GRAPH,
   std::optional<int> c                          = std::make_optional<int>(DEFAULT_CONST_C));
 
+/**
+ * @}
+ */
 };  // end namespace  cuvs::cluster::agglomerative