Update notes

Author: jlukic

RELEASE-NOTES.md

@@ -4,6 +4,8 @@
 
 **Build**
 - **Gulp** - Updated all tasks to work with Gulp 4. This should fix SUI to install correctly on Node 12 or greater (see [Gulp3 Issue](https://github.com/gulpjs/gulp/issues/2324) for more details)
+- **Theme** - Allow site's global site theme to be missing #6876 **Thanks @cruzdanillo**
+- **Meteor** - Fix issue with misuse of `api.addAssets` #6790 **Thanks @gimco**
 
 **Examples**
 - **Sticky** - Adds new example for sticky to highlight behavior when sticky/context height varies