match spans on instrumentation library

internal/processor/filterspan/config.go

@@ -77,10 +77,13 @@ type MatchProperties struct {
 	Services []string `mapstructure:"services"`
 
 	// Resources specify the list of items to match the resources against.
-	// A match occurs if the span's service name matches at least one item in this list.
+	// A match occurs if the span's resources matches at least one item in this list.
 	// This is an optional field.
 	Resources []Attribute `mapstructure:"resource"`
 
+	// Libraries specify the list of items to match the implementation library against.
+	// A match occurs if the span's implementation library matches at least one item in this list.
+	// This is an optional field.
 	Libraries []InstrumentationLibrary `mapstructure:"libraries"`
 
 	// SpanNames specify the list of items to match span name against.
@@ -105,6 +108,7 @@ type Attribute struct {
 	Value interface{} `mapstructure:"value"`
 }
 
+// InstrumentationLibrary specifies the instrumentation library and optional version to match against.
 type InstrumentationLibrary struct {
 	Name string `mapstructure:"name"`
 	// version match