Remove @api directive. (#3566)

Author: kallentu

lib/src/model/directives/categorization.dart

@@ -7,7 +7,7 @@ import 'package:dartdoc/src/model/model.dart';
 import 'package:meta/meta.dart';
 
 final RegExp _categoryRegExp = RegExp(
-    r'[ ]*{@(api|category|subCategory|image|samples) (.+?)}[ ]*\n?',
+    r'[ ]*{@(category|subCategory|image|samples) (.+?)}[ ]*\n?',
     multiLine: true);
 
 /// Mixin parsing the `@category` directive for ModelElements.
@@ -28,7 +28,6 @@ mixin Categorization on DocumentationComment implements Indexable {
       _hasCategorization = true;
       switch (match[1]) {
         case 'category':
-        case 'api':
           categorySet.add(match[2]!.trim());
         case 'subCategory':
           subCategorySet.add(match[2]!.trim());

lib/src/model/documentation_comment.dart

@@ -158,7 +158,6 @@ mixin DocumentationComment
     'youtube',
 
     // Other directives, parsed by `model/directives/*.dart`:
-    'api',
     'canonicalFor',
     'category',
     'hideConstantImplementations',