Release minor version of Reffy - v6.3.0

New features:
- Record and use HTTP cache information to skip unnecessary crawling and
processing (#856)
- Check cache validity before launching browser tab (#858)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "reffy",
-  "version": "6.2.2",
+  "version": "6.3.0",
   "description": "W3C/WHATWG spec dependencies exploration companion. Features a short set of tools to study spec references as well as WebIDL term definitions and references found in W3C specifications.",
   "repository": {
     "type": "git",