Add brief introduction of lowest latency memspace

Author: kswiecicki

README.md

@@ -229,6 +229,11 @@ Can be retrieved using umfMemspaceHighestCapacityGet.
 Memspace backed by an aggregated list of NUMA nodes identified as highest bandwidth after selecting each available NUMA node as the initiator.
 Querying the bandwidth value requires HMAT support on the platform. Calling `umfMemspaceHighestBandwidthGet()` will return NULL if it's not supported.
 
+#### Lowest latency memspace
+
+Memspace backed by an aggregated list of NUMA nodes identified as lowest latency after selecting each available NUMA node as the initiator.
+Querying the latency value requires HMAT support on the platform. Calling `umfMemspaceLowestLatencyGet()` will return NULL if it's not supported.
+
 ### Proxy library
 
 UMF provides the UMF proxy library (`umf_proxy`) that makes it possible

include/umf/memspace.h

@@ -57,12 +57,14 @@ umf_memspace_handle_t umfMemspaceHostAllGet(void);
 umf_memspace_handle_t umfMemspaceHighestCapacityGet(void);
 
 /// \brief Retrieves predefined highest bandwidth memspace.
-/// \return highest bandwidth memspace handle on success or NULL on failure.
+/// \return highest bandwidth memspace handle on success or NULL on
+///         failure (no HMAT support).
 ///
 umf_memspace_handle_t umfMemspaceHighestBandwidthGet(void);
 
 /// \brief Retrieves predefined lowest latency memspace.
-/// \return lowest latency memspace handle on success or NULL on failure.
+/// \return lowest latency memspace handle on success or NULL on
+///         failure (no HMAT support).
 ///
 umf_memspace_handle_t umfMemspaceLowestLatencyGet(void);