Create PRINCIPLES.MD (#696)

Creating a page to communicate agreed-upon FURN principles

PRINCIPLES.MD

@@ -0,0 +1,15 @@
+> THIS DOCUMENT IS A DRAFT
+
+# Operating Principles of Fluent UI React Native (FURN)
+- FURN is multi modal – give customers what they want 
+  - Some controls are JS
+  - Some are wrapped-native
+  - Some offer both implementations
+- Cross-platform consistency is an important appeal, but exceptions should be made to account for uniqueness in native platforms – let the platform shines
+  - Align on names and props whenever appropriate, but don't be dogmatic  
+  - Use Fluent UI Web as inspiration, but don't be blocked if full alignment is yet achievable
+  - Make local per-platform decisions when appropriate
+- Some platforms are more similar than the others, and we should set expectations accordingly – drive higher consistency within a class than across classes
+  - Desktop OSes belong to a class 
+  - Mobile OSes belong to another class
+  - Web is yet another class