Expand docs comments

Signed-off-by: Linas Medziunas <linas.medziunas@gmail.com>

model/histogram/float_histogram.go

@@ -307,6 +307,7 @@ func (h *FloatHistogram) Sub(other *FloatHistogram) *FloatHistogram {
 // Exact match is when there are no new buckets (even empty) and no missing buckets,
 // and all the bucket values match. Spans can have different empty length spans in between,
 // but they must represent the same bucket layout to match.
+// Non-metadata float fields (Sum, Count, ZeroCount) are compared as binary (using math.Float64bits).
 func (h *FloatHistogram) Equals(h2 *FloatHistogram) bool {
 	if h2 == nil {
 		return false

model/histogram/histogram.go

@@ -172,6 +172,7 @@ func (h *Histogram) CumulativeBucketIterator() BucketIterator[uint64] {
 // Exact match is when there are no new buckets (even empty) and no missing buckets,
 // and all the bucket values match. Spans can have different empty length spans in between,
 // but they must represent the same bucket layout to match.
+// Non-metadata float field (Sum) is compared as binary (using math.Float64bits).
 func (h *Histogram) Equals(h2 *Histogram) bool {
 	if h2 == nil {
 		return false