Add more details for AttributeValue warnning

Author: zurex

api/include/opentelemetry/common/attribute_value.h

@@ -23,7 +23,8 @@ namespace common
 ///    (IEEE 754-1985) or signed 64 bit integer.
 ///  - Homogenous arrays of primitive type values.
 ///
-/// \warning The OpenTelemetry C++ API does not support the following attribute
+/// \warning The OpenTelemetry C++ API does not support the following attribute:
+///  uint64_t, nostd::span<const uint64_t>, and nostd::span<uint8_t> types.
 /// \parblock The OpenTelemetry C++ API currently supports several attribute
 /// value types that are not covered by the OpenTelemetry specification:
 ///  - \c uint64_t