common: Fix golint errors

common/errors/errors.go:21:1: comment on exported var FeatureNotAvailableErr should be of the form "FeatureNotAvailableErr ..."
common/errors/errors.go:23:5: error var FeatureNotAvailableErr should have name of the form ErrFoo
common/maps/scratch.go:76:1: comment on exported method Scratch.Delete should be of the form "Delete ..."
common/maps/scratch.go:133:1: exported function NewScratch should have comment or be unexported
common/types/types.go:44:1: exported function NewKeyValuesStrings should have comment or be unexported

common/errors/errors.go

@@ -18,6 +18,8 @@ import (
 	"errors"
 )
 
+// ErrFeatureNotAvailable denotes that a feature is unavailable.
+//
 // We will, at least to begin with, make some Hugo features (SCSS with libsass) optional,
 // and this error is used to signal those situations.
-var FeatureNotAvailableErr = errors.New("this feature is not available in your current Hugo version")
+var ErrFeatureNotAvailable = errors.New("this feature is not available in your current Hugo version")

common/maps/scratch.go

@@ -73,7 +73,7 @@ func (c *Scratch) Set(key string, value interface{}) string {
 	return ""
 }
 
-// Reset deletes the given key
+// Delete deletes the given key.
 func (c *Scratch) Delete(key string) string {
 	c.mu.Lock()
 	delete(c.values, key)
@@ -81,7 +81,7 @@ func (c *Scratch) Delete(key string) string {
 	return ""
 }
 
-// Get returns a value previously set by Add or Set
+// Get returns a value previously set by Add or Set.
 func (c *Scratch) Get(key string) interface{} {
 	c.mu.RLock()
 	val := c.values[key]
@@ -104,7 +104,7 @@ func (c *Scratch) SetInMap(key string, mapKey string, value interface{}) string
 	return ""
 }
 
-// GetSortedMapValues returns a sorted map previously filled with SetInMap
+// GetSortedMapValues returns a sorted map previously filled with SetInMap.
 func (c *Scratch) GetSortedMapValues(key string) interface{} {
 	c.mu.RLock()
 
@@ -130,6 +130,7 @@ func (c *Scratch) GetSortedMapValues(key string) interface{} {
 	return sortedArray
 }
 
+// NewScratch returns a new instance Scratch.
 func NewScratch() *Scratch {
 	return &Scratch{values: make(map[string]interface{})}
 }

common/types/types.go

@@ -41,6 +41,8 @@ func (k KeyValues) String() string {
 	return fmt.Sprintf("%v: %v", k.Key, k.Values)
 }
 
+// NewKeyValuesStrings takes a given key and slice of values and returns a new
+// KeyValues struct.
 func NewKeyValuesStrings(key string, values ...string) KeyValues {
 	iv := make([]interface{}, len(values))
 	for i := 0; i < len(values); i++ {