docs(metric): document public interfaces with versioning policy (#3441)

* docs(metric): document public interfaces with versioning policy

* docs(metric): remove versioning policy warning from interfaces without public method(s)

metric/instrument/asyncfloat64/asyncfloat64.go

@@ -22,6 +22,8 @@ import (
 )
 
 // InstrumentProvider provides access to individual instruments.
+//
+// Warning: methods may be added to this interface in minor releases.
 type InstrumentProvider interface {
 	// Counter creates an instrument for recording increasing values.
 	Counter(name string, opts ...instrument.Option) (Counter, error)
@@ -34,6 +36,8 @@ type InstrumentProvider interface {
 }
 
 // Counter is an instrument that records increasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Counter interface {
 	// Observe records the state of the instrument to be x. Implementations
 	// will assume x to be the cumulative sum of the count.
@@ -47,6 +51,8 @@ type Counter interface {
 }
 
 // UpDownCounter is an instrument that records increasing or decreasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type UpDownCounter interface {
 	// Observe records the state of the instrument to be x. Implementations
 	// will assume x to be the cumulative sum of the count.
@@ -60,6 +66,8 @@ type UpDownCounter interface {
 }
 
 // Gauge is an instrument that records independent readings.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Gauge interface {
 	// Observe records the state of the instrument to be x.
 	//

metric/instrument/asyncint64/asyncint64.go

@@ -22,6 +22,8 @@ import (
 )
 
 // InstrumentProvider provides access to individual instruments.
+//
+// Warning: methods may be added to this interface in minor releases.
 type InstrumentProvider interface {
 	// Counter creates an instrument for recording increasing values.
 	Counter(name string, opts ...instrument.Option) (Counter, error)
@@ -34,6 +36,8 @@ type InstrumentProvider interface {
 }
 
 // Counter is an instrument that records increasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Counter interface {
 	// Observe records the state of the instrument to be x. Implementations
 	// will assume x to be the cumulative sum of the count.
@@ -47,6 +51,8 @@ type Counter interface {
 }
 
 // UpDownCounter is an instrument that records increasing or decreasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type UpDownCounter interface {
 	// Observe records the state of the instrument to be x. Implementations
 	// will assume x to be the cumulative sum of the count.
@@ -60,6 +66,8 @@ type UpDownCounter interface {
 }
 
 // Gauge is an instrument that records independent readings.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Gauge interface {
 	// Observe records the state of the instrument to be x.
 	//

metric/instrument/syncfloat64/syncfloat64.go

@@ -22,6 +22,8 @@ import (
 )
 
 // InstrumentProvider provides access to individual instruments.
+//
+// Warning: methods may be added to this interface in minor releases.
 type InstrumentProvider interface {
 	// Counter creates an instrument for recording increasing values.
 	Counter(name string, opts ...instrument.Option) (Counter, error)
@@ -32,6 +34,8 @@ type InstrumentProvider interface {
 }
 
 // Counter is an instrument that records increasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Counter interface {
 	// Add records a change to the counter.
 	Add(ctx context.Context, incr float64, attrs ...attribute.KeyValue)
@@ -40,6 +44,8 @@ type Counter interface {
 }
 
 // UpDownCounter is an instrument that records increasing or decreasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type UpDownCounter interface {
 	// Add records a change to the counter.
 	Add(ctx context.Context, incr float64, attrs ...attribute.KeyValue)
@@ -48,6 +54,8 @@ type UpDownCounter interface {
 }
 
 // Histogram is an instrument that records a distribution of values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Histogram interface {
 	// Record adds an additional value to the distribution.
 	Record(ctx context.Context, incr float64, attrs ...attribute.KeyValue)

metric/instrument/syncint64/syncint64.go

@@ -22,6 +22,8 @@ import (
 )
 
 // InstrumentProvider provides access to individual instruments.
+//
+// Warning: methods may be added to this interface in minor releases.
 type InstrumentProvider interface {
 	// Counter creates an instrument for recording increasing values.
 	Counter(name string, opts ...instrument.Option) (Counter, error)
@@ -32,6 +34,8 @@ type InstrumentProvider interface {
 }
 
 // Counter is an instrument that records increasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Counter interface {
 	// Add records a change to the counter.
 	Add(ctx context.Context, incr int64, attrs ...attribute.KeyValue)
@@ -40,6 +44,8 @@ type Counter interface {
 }
 
 // UpDownCounter is an instrument that records increasing or decreasing values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type UpDownCounter interface {
 	// Add records a change to the counter.
 	Add(ctx context.Context, incr int64, attrs ...attribute.KeyValue)
@@ -48,6 +54,8 @@ type UpDownCounter interface {
 }
 
 // Histogram is an instrument that records a distribution of values.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Histogram interface {
 	// Record adds an additional value to the distribution.
 	Record(ctx context.Context, incr int64, attrs ...attribute.KeyValue)

metric/meter.go

@@ -26,6 +26,8 @@ import (
 
 // MeterProvider provides access to named Meter instances, for instrumenting
 // an application or library.
+//
+// Warning: methods may be added to this interface in minor releases.
 type MeterProvider interface {
 	// Meter creates an instance of a `Meter` interface. The instrumentationName
 	// must be the name of the library providing instrumentation. This name may
@@ -36,6 +38,8 @@ type MeterProvider interface {
 }
 
 // Meter provides access to instrument instances for recording metrics.
+//
+// Warning: methods may be added to this interface in minor releases.
 type Meter interface {
 	// AsyncInt64 is the namespace for the Asynchronous Integer instruments.
 	//