Remove some obsolete references to GrepFilter

Looks like GrepFilter was generalized to Filter.

kyaml/yaml/filters.go

@@ -31,7 +31,7 @@ var Filters = map[string]func() Filter{
 	"TeePiper":          func() Filter { return &TeePiper{} },
 }
 
-// YFilter wraps the GrepFilter interface so the filter can be represented as
+// YFilter wraps the Filter interface so the filter can be represented as
 // data and can be unmarshalled into a struct from a yaml config file.
 // This allows Pipelines to be expressed as data rather than code.
 type YFilter struct {
@@ -54,7 +54,7 @@ func (y *YFilter) UnmarshalYAML(unmarshal func(interface{}) error) error {
 			knownFilters = append(knownFilters, k)
 		}
 		sort.Strings(knownFilters)
-		return fmt.Errorf("unsupported GrepFilter Kind %s:  may be one of: [%s]",
+		return fmt.Errorf("unsupported Filter Kind %s:  may be one of: [%s]",
 			meta.Kind, strings.Join(knownFilters, ","))
 	}
 	y.Filter = filter()

kyaml/yaml/rnode.go

@@ -277,14 +277,14 @@ func (rn *RNode) GetMeta() (ResourceMeta, error) {
 	return m, nil
 }
 
-// Pipe sequentially invokes each GrepFilter, and passes the result to the next
-// GrepFilter.
+// Pipe sequentially invokes each Filter, and passes the result to the next
+// Filter.
 //
 // Analogous to http://www.linfo.org/pipes.html
 //
-// * rn is provided as input to the first GrepFilter.
-// * if any GrepFilter returns an error, immediately return the error
-// * if any GrepFilter returns a nil RNode, immediately return nil, nil
+// * rn is provided as input to the first Filter.
+// * if any Filter returns an error, immediately return the error
+// * if any Filter returns a nil RNode, immediately return nil, nil
 // * if all Filters succeed with non-empty results, return the final result
 func (rn *RNode) Pipe(functions ...Filter) (*RNode, error) {
 	// check if rn is nil to make chaining Pipe calls easier