Improve topics

Writerside/labels.list

@@ -17,6 +17,10 @@
         The implementation of the functionality available for installation
         of "type-lang/reader" component
     </primary-label>
+    <primary-label id="experimental" name="Special Feature" short-name="Extra" color="tangerine">
+        This is a unique functionality that is not supported by other popular
+        third-party tools (e.g. PHPStan or Psalm) and has no alternatives.
+    </primary-label>
 
     <secondary-label id="psalm" name="Psalm" color="blue">
         Also partially or fully supported by Psalm Linter.

Writerside/topics/language/callable-types.md

@@ -235,6 +235,7 @@ _before the type_ or _before the parameter name._
 
 ## Attributes
 
+<primary-label ref="experimental"/>
 <secondary-label ref="tl1.2"/>
 
 Each callable parameter allows you to define list of additional attributes.

Writerside/topics/language/generic-types.md

@@ -163,6 +163,7 @@ In addition to modern list declarations such as `list<int>` or
 
 ## Attributes
 
+<primary-label ref="experimental"/>
 <secondary-label ref="tl1.1"/>
 
 Each template argument allows you to define list of additional attributes. 

Writerside/topics/language/shape-types.md

@@ -124,6 +124,7 @@ array{
 
 ## Attributes
 
+<primary-label ref="experimental"/>
 <secondary-label ref="tl1.1"/>
 
 Each shape field allows you to define list of additional attributes.