Merge "Generate reference nav to _book.yaml for devsite builds." into mnc-mr-docs
am: dc55c97296

* commit 'dc55c97296b0cc7d50d56013d417444c9b012ce2':
  Generate reference nav to _book.yaml for devsite builds.

Change-Id: Id90b7d082e780530943f2a9e25f42edbc634658d