Thrift Object Model v1.1.1

Summary:
From Changelog:

[`PATCH`]:
1.  Reworded Common Field Preservation and added Example
2. Fixed indentation of `embed` operation details, some typos and nits.

Reviewed By: praihan, hchokshi

Differential Revision: D86697186

fbshipit-source-id: a43e5ce76f1ff8fe1d051d21d7f0ed24fcf99678

Author: aristidisp