README.md: Reference Read The Docs deployment

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>

README.md

@@ -13,6 +13,13 @@ project. It does that by aggregating multiple `sphinx` projects part of
 OpenHarmony ecosystem and consolidating all these documentation trees as part of
 one, project-wide, `sphinx` project.
 
+## Read The Docs
+
+As part of the OpenHarmony infrastructure, this documentation is pushed to a
+Read The Docs project. You can inspect the `latest` version
+[online](https://openharmony.readthedocs.io/en/latest) or download it as
+[PDF](https://openharmony.readthedocs.io/_/downloads/en/latest/pdf/).
+
 ## Building the docs
 
 As per the current implementation for satisfying aggregation of multiple