Add to list of blocks

docs/developer/blocks/README.md

@@ -1,6 +1,12 @@
 # Blocks in GatherPress
 
-1. All blocks in general (LINK to /docs/user/...)
+1. All blocks in general <!-- Maybe better put under /docs/user/... and just link it? -->
+
+    1. Add to Calendar
+
+       Allows a user to add an event to their preferred calendar application.
+
+    2. ...
 2. [Hookable patterns for events & venues](./hookable-patterns/)
     - Add to or Remove blocks from the post type block templates
 3. [Slots & fills in GatherPress Admin UI](./slot-fills/)