allow release-date and release-versions to be null

Author: mansona

lib/frontmatter-linter.js

@@ -62,17 +62,15 @@ module.exports = class FrontmatterLinter {
         },
       },
       'release-date': {
-        type: 'date',
+        type: ['date', 'null'],
         required: true,
-        allowEmpty: false,
         messages: {
           type: 'must be a date formatted YYYY-MM-DD',
         },
       },
       'release-versions': {
-        type: 'object',
+        type: ['object', 'null'],
         required: true,
-        allowEmpty: true,
         conform(packages) {
           for (const p in packages) {
             if (!semver.valid(packages[p])) {