docs: 2.2 release announcement updated

docs/blog/posts/2.2.0-released.md

@@ -299,6 +299,27 @@ is why it was renamed to `symbol_text` (:boom: **breaking change** :boom:).
     inline constexpr struct ohm final : named_unit<{u8"Ω", "ohm"}, volt / ampere> {} ohm;
     ```
 
+
+## Changes to dimension and quantity specification definitions
+
+Similarly to units, now also all dimensions and quantity specifications have to be marked final
+(:boom: **breaking change** :boom:).
+
+=== "Now"
+
+    ```cpp
+    inline constexpr struct dim_length final : base_dimension<"L"> {} dim_length;
+    inline constexpr struct length final : quantity_spec<dim_length> {} length;
+    ```
+
+=== "Before"
+
+    ```cpp
+    inline constexpr struct dim_length : base_dimension<"L"> {} dim_length;
+    inline constexpr struct length : quantity_spec<dim_length> {} length;
+    ```
+
+
 ## Improved text output
 
 With this release, we can print not only whole quantities but also just their units or dimensions.