geojson: update readmes for external jsonifier support

README.md

@@ -107,6 +107,10 @@ for _, f := range fc {
 }
 ```
 
+The library supports third party "encoding/json" replacements
+such [github.com/json-iterator/go](https://github.com/json-iterator/go).
+See the [geojson](geojson) readme for more details.
+
 ## Mapbox Vector Tiles
 
 The [encoding/mvt](encoding/mvt) sub-package implements Marshalling and

geojson/README.md

@@ -66,9 +66,9 @@ fc.ExtraMembers["timestamp"] // == "2020-06-15T01:02:03Z"
 // base featureCollection object.
 ```
 
-## Performance Performance Performance
+## Performance
 
-If GeoJSON encoding/decoding performance is critical consider using a
+For performance critical applications, consider a
 third party replacement of "encoding/json" like [github.com/json-iterator/go](https://github.com/json-iterator/go)
 
 This can be enabled with something like this:
@@ -82,7 +82,6 @@ import (
 var c = jsoniter.Config{
   EscapeHTML:              true,
   SortMapKeys:             false,
-  ValidateJsonRawMessage:  false,
   MarshalFloatWith6Digits: true,
 }.Froze()
 
@@ -126,7 +125,3 @@ f.Properties.MustFloat64(key string, def ...float64) float64
 f.Properties.MustInt(key string, def ...int) int
 f.Properties.MustString(key string, def ...string) string
 ```
-
-```
-
-```

geojson/json.go

@@ -15,9 +15,9 @@ import "encoding/json"
 //	var c = jsoniter.Config{
 //	  EscapeHTML:              true,
 //	  SortMapKeys:             false,
-//	  ValidateJsonRawMessage:  false,
 //	  MarshalFloatWith6Digits: true,
 //	}.Froze()
+//
 //	orb.CustomJSONMarshaler = c
 //	orb.CustomJSONUnmarshaler = c
 //
@@ -39,9 +39,9 @@ var CustomJSONMarshaler interface {
 //	var c = jsoniter.Config{
 //	  EscapeHTML:              true,
 //	  SortMapKeys:             false,
-//	  ValidateJsonRawMessage:  false,
 //	  MarshalFloatWith6Digits: true,
 //	}.Froze()
+//
 //	orb.CustomJSONMarshaler = c
 //	orb.CustomJSONUnmarshaler = c
 //