Fix linter errors

pkg/buildinfo/buildinfo.go

@@ -13,18 +13,22 @@ var (
 	date    = unknown
 )
 
+// Version returns version from git describe.
 func Version() string {
 	return version
 }
 
+// Commit returns commit hash.
 func Commit() string {
 	return commit
 }
 
+// Date returns date of build in RFC3339 format.
 func Date() string {
 	return date
 }
 
+// Get returns build info summary.
 func Get() *Info {
 	return &Info{
 		Version: Version(),
@@ -33,13 +37,16 @@ func Get() *Info {
 	}
 }
 
+// Info is build info summary.
 type Info struct {
 	Version string `json:"version"`
 	Commit  string `json:"commit"`
 	Date    string `json:"date"`
 }
 
-func (info *Info) WriteTo(w io.Writer) (n int, err error) {
+// WriteTo writes build info summary to io.Writer.
+func (info *Info) WriteTo(w io.Writer) (int64, error) {
 	msg := fmt.Sprintf("Version %q built on %q agaist commit %q\n", info.Version, info.Date, info.Commit)
-	return w.Write([]byte(msg))
+	n, err := w.Write([]byte(msg))
+	return int64(n), err
 }