Changelog update

Related to #9020

Author: zdrawku

Diff for: CHANGELOG.md

@@ -5,6 +5,16 @@ All notable changes for each version of this project will be documented in this
 ## 12.1.0
 
 ### New Features
+- `igxGrid`
+    - New `additionalTemplateContext` column input:
+
+    ```html
+    <igx-column [additionalTemplateContext]="contextObject">
+      <ng-template igxCell let-cell="cell" let-props="additionalTemplateContext">
+         {{ props }}
+      </ng-template>
+    </igx-column>
+    ```
 - `Toolbar Actions`
     - Exposed a new input property `overlaySettings` for all column actions (`hiding` | `pinning` | `advanced filtering` | `exporter`). Example below: