Restore public API reference documentation

source.go

@@ -13,13 +13,15 @@ type Source struct{ value engine.Source }
 // File returns a source that reopens path for every load attempt.
 func File(path string) Source { return Source{value: engine.File(path)} }
 
-// Bytes snapshots data immediately.
+// Bytes snapshots data immediately. Label must be nonempty and safe to display;
+// constructor problems are reported when the source is consumed.
 func Bytes(label string, data []byte) Source { return Source{value: engine.Bytes(label, data)} }
 
-// Reader returns a single-use source. Copies share the same single-use claim.
+// Reader returns a single-use source. ConfigKit consumes input but never closes it.
+// Copies of the returned Source share the same single-use claim.
 func Reader(label string, input io.Reader) Source { return Source{value: engine.Reader(label, input)} }
 
-// NoSource explicitly selects defaults-only input.
+// NoSource explicitly selects a defaults-only input. It creates no source record.
 func NoSource() Source { return Source{value: engine.NoSource()} }
 
 func (s Source) toEngine() engine.Source { return s.value }