Apply suggestions from code review

Co-authored-by: Claas Augner <[email protected]>

Author: foolip

css/types/sibling-count.json

@@ -3,6 +3,7 @@
     "types": {
       "sibling-count": {
         "__compat": {
+          "description": "`sibling-count()`",
           "spec_url": "https://drafts.csswg.org/css-values-5/#funcdef-sibling-count",
           "support": {
             "chrome": {
@@ -11,7 +12,8 @@
             "chrome_android": "mirror",
             "edge": "mirror",
             "firefox": {
-              "version_added": false
+              "version_added": false,
+              "impl_url": "https://bugzil.la/1953973"
             },
             "firefox_android": "mirror",
             "ie": {

css/types/sibling-index.json

@@ -3,6 +3,7 @@
     "types": {
       "sibling-index": {
         "__compat": {
+          "description": "`sibling-index()`",
           "spec_url": "https://drafts.csswg.org/css-values-5/#funcdef-sibling-index",
           "support": {
             "chrome": {
@@ -11,7 +12,8 @@
             "chrome_android": "mirror",
             "edge": "mirror",
             "firefox": {
-              "version_added": false
+              "version_added": false,
+              "impl_url": "https://bugzil.la/1953973"
             },
             "firefox_android": "mirror",
             "ie": {