build: fix lint errors when re-enabling revive exported & package-comments

fs/open_options.go

@@ -276,18 +276,22 @@ func (o MetadataOption) Mandatory() bool {
 	return false
 }
 
+// ChunkOption defines an Option which returns a preferred chunk size
 type ChunkOption struct {
 	ChunkSize int64
 }
 
+// Header formats the option as an http header
 func (o *ChunkOption) Header() (key string, value string) {
 	return "chunkSize", fmt.Sprintf("%v", o.ChunkSize)
 }
 
+// Mandatory returns whether the option must be parsed or can be ignored
 func (o *ChunkOption) Mandatory() bool {
 	return false
 }
 
+// String formats the option into human-readable form
 func (o *ChunkOption) String() string {
 	return fmt.Sprintf("ChunkOption(%v)", o.ChunkSize)
 }