Fix golint issues caused by typos (#8769)

Signed-off-by: Hu Shuai <hus.fnst@cn.fujitsu.com>

discovery/aws/ec2.go

@@ -73,7 +73,7 @@ func init() {
 	discovery.RegisterConfig(&EC2SDConfig{})
 }
 
-// Filter is the configuration for filtering EC2 instances.
+// EC2Filter is the configuration for filtering EC2 instances.
 type EC2Filter struct {
 	Name   string   `yaml:"name"`
 	Values []string `yaml:"values"`
@@ -128,7 +128,7 @@ func (c *EC2SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	return nil
 }
 
-// Discovery periodically performs EC2-SD requests. It implements
+// EC2Discovery periodically performs EC2-SD requests. It implements
 // the Discoverer interface.
 type EC2Discovery struct {
 	*refresh.Discovery

discovery/aws/lightsail.go

@@ -110,7 +110,7 @@ func (c *LightsailSDConfig) UnmarshalYAML(unmarshal func(interface{}) error) err
 	return nil
 }
 
-// Discovery periodically performs Lightsail-SD requests. It implements
+// LightsailDiscovery periodically performs Lightsail-SD requests. It implements
 // the Discoverer interface.
 type LightsailDiscovery struct {
 	*refresh.Discovery

discovery/eureka/eureka.go

@@ -116,7 +116,7 @@ type Discovery struct {
 	server string
 }
 
-// New creates a new Eureka discovery for the given role.
+// NewDiscovery creates a new Eureka discovery for the given role.
 func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) {
 	rt, err := config.NewRoundTripperFromConfig(conf.HTTPClientConfig, "eureka_sd", config.WithHTTP2Disabled())
 	if err != nil {