Add OTA documentation

Add documentation and notes on the OTA stack.

Signed-off-by: Zygmunt Krynicki <zygmunt.krynicki@huawei.com>
Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>
Signed-off-by: Kareem Zarka <kareem.zarka@huawei.com>

index.rst

@@ -66,6 +66,12 @@ daily life.
    oniro/hardware-support/index
    building-project-documentation
 
+.. toctree::
+   :caption: OS Features
+   :maxdepth: 2
+   
+   ota
+
 .. toctree::
    :caption: Supported Technologies
    :maxdepth: 2