[10.x] @session Blade Directive (#9223)

* Add docs for @session blade directive

* Update blade.md

---------

Co-authored-by: Taylor Otwell <taylor@laravel.com>

blade.md

@@ -301,6 +301,19 @@ You may use the `sectionMissing` directive to determine if a section does not ha
 @endif
 ```
 
+<a name="session-directives"></a>
+#### Session Directives
+
+The `@session` directive may be used to determine if a [session](/docs/{{version}}/session) value exists. If the session value exists, the template contents within the `@session` and `@endsession` directives will be evaluated. Within the `@session` directive's contents, you may echo the `$value` variable to display the session value:
+
+```blade
+@session('status')
+    <div class="p-4 bg-green-100">
+        {{ $value }}
+    </div>
+@endsession
+```
+
 <a name="switch-statements"></a>
 ### Switch Statements