Add a placeholder page for live vs. frozen objects

Author: dacharyc

source/index.txt

@@ -18,6 +18,7 @@ Welcome to the Atlas Device SDK Docs
    Quick Start </sdk/quick-start>
    Model Data </sdk/model-data>
    Open & Manage Database Files </sdk/files>
+   Live vs. Frozen Objects </sdk/live-frozen-objects>
    Read & Write Data </sdk/crud>
    React to Changes </sdk/react-to-changes>
    Access Atlas </sdk/atlas>

source/sdk/live-frozen-objects.txt

@@ -0,0 +1,15 @@
+.. _sdks-live-and-frozen-objects:
+
+=======================
+Live and Frozen Objects
+=======================
+
+.. contents:: On this page
+   :local:
+   :backlinks: none
+   :depth: 2
+   :class: singlecol
+
+Placeholder page for consolidated content about SDK objects being live by
+default, except when frozen, and how that differs from Kotlin's frozen
+architecture.