* WIP more guides and tutorials for the docs

* Update Guides and structure

* Update Guides and structure

+ Test documentation build on Clear Linux OS;
+ Fix a few links and redirs.
+ Note rc-naming conventions in doc may be tag-generalized.

* documentation supports various rc-naming conventions

* Add instructions on building nGraph bridge from src

* Update ngtf bridge versions to 0.14.1 and TensorFlow's bazel dependency to 0.24.1

* Use consistent file naming on all BE indexes

* Fix comma

* Templatize versioning for releases starting 0.20 and add placeholders for changes by components

* Remove typo

* Minor formatting fixed

* Document how to find or display built version of nGraph

* Start a r0.21 for doc that also fixes broken link and typo

* Correct use of console command context for version check

* Minor fixes to doc-contributor-README

* Docs for version 0.21

* Ensure docs build without error

* Assign ownership project README and intro for new ngraph.ai site to Straw

* Note deprecated Tensor API in doc

* Update to generic versioning on core doc for importing via built wheels

* Resolve merge conflicts leftover from v20 version request changes

* remove typo and suggested use of prebuilt LLVM since newer OSes do not have them available

* Update to latest

* Update with review from PR and ngraph bridge team

* Update right section with review from PR and ngraph bridge team

* Ensure doc example folders have owners from the component

* Push edit of tensorflow_connect to v0.22 docs

* Update Python wheel building instructions to newer version